Hi Marek,

Thank you for the patchset --- and my apologies for reviewing it so late.

On Mon, May 20, 2019 at 10:18:12PM +0200, Marek Vasut wrote:
> Add driver for the Intersil ISL7998x BT656-to-MIPI-CSI2 video decoder.
> This chip supports 1/2/4 analog video inputs and converts them into
> 1/2/4 VCs in MIPI CSI2 stream.
> 
> This driver currently supports ISL79987 and both 720x480 and 720x576
> resolutions, however as per specification, all inputs must use the
> same resolution and standard. The only supported pixel format is now
> YUYV/YUV422. The chip should support RGB565 on the CSI2 as well, but
> this is currently unsupported.
> 
> Signed-off-by: Marek Vasut <ma...@denx.de>
> Cc: Sakari Ailus <sakari.ai...@linux.intel.com>
> Cc: Mauro Carvalho Chehab <mchehab+sams...@kernel.org>
> Cc: Rob Herring <robh...@kernel.org>
> To: linux-media@vger.kernel.org
> ---
>  drivers/media/i2c/Kconfig    |    6 +
>  drivers/media/i2c/Makefile   |    1 +
>  drivers/media/i2c/isl7998x.c | 1111 ++++++++++++++++++++++++++++++++++
>  3 files changed, 1118 insertions(+)
>  create mode 100644 drivers/media/i2c/isl7998x.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 7793358ab8b3..af2ea08d6c59 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -929,6 +929,12 @@ config VIDEO_NOON010PC30
>       help
>         This driver supports NOON010PC30 CIF camera from Siliconfile
>  
> +config VIDEO_ISL7998X
> +     tristate "Intersil ISL7998x support"
> +     depends on I2C && VIDEO_V4L2
> +     help
> +       This driver supports Intersil ISL7998x BT656-to-MIPI-CSI2 bridge.
> +
>  source "drivers/media/i2c/m5mols/Kconfig"
>  
>  config VIDEO_RJ54N1
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index d8ad9dad495d..a66f105a7bcc 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -113,6 +113,7 @@ obj-$(CONFIG_VIDEO_IMX258)        += imx258.o
>  obj-$(CONFIG_VIDEO_IMX274)   += imx274.o
>  obj-$(CONFIG_VIDEO_IMX319)   += imx319.o
>  obj-$(CONFIG_VIDEO_IMX355)   += imx355.o
> +obj-$(CONFIG_VIDEO_ISL7998X) += isl7998x.o
>  obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
>  
>  obj-$(CONFIG_SDR_MAX2175) += max2175.o
> diff --git a/drivers/media/i2c/isl7998x.c b/drivers/media/i2c/isl7998x.c
> new file mode 100644
> index 000000000000..858e98d8b494
> --- /dev/null
> +++ b/drivers/media/i2c/isl7998x.c
> @@ -0,0 +1,1111 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intersil ISL7998x BT656-to-MIPI-CSI2 driver
> + *
> + * Copyright (C) 2018-2019 Marek Vasut <ma...@denx.de>
> + */
> +#include <linux/videodev2.h>
> +#include <linux/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/i2c.h>
> +#include <linux/log2.h>
> +#include <linux/module.h>
> +#include <linux/of_graph.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/v4l2-mediabus.h>
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-clk.h>
> +#include <media/v4l2-common.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>

Alphabetical order, please.

> +
> +#define ISL7998x_WIDTH                       720
> +#define ISL7998x_HEIGHT                      480
> +#define ISL7998x_INPUTS                      4
> +
> +#define V4L2_CID_TEST_PATTERN_COLOR  (V4L2_CID_USER_BASE | 0x1001)
> +#define V4L2_CID_TEST_PATTERN_CHANNELS       (V4L2_CID_USER_BASE | 0x1002)
> +#define V4L2_CID_TEST_PATTERN_BARS   (V4L2_CID_USER_BASE | 0x1003)
> +
> +#define ISL7998x_REG(page, reg)              (((page) << 8) | (reg))
> +
> +#define ISL7998x_REG_Pn_SIZE                 256
> +#define ISL7998x_REG_Pn_BASE(n)                      ((n) * 
> ISL7998x_REG_Pn_SIZE)
> +
> +#define ISL7998x_REG_Px_DEC_PAGE(page)               ISL7998x_REG((page), 
> 0xff)
> +#define ISL7998x_REG_Px_DEC_PAGE_MASK                0xf
> +#define ISL7998x_REG_P0_PRODUCT_ID_CODE              ISL7998x_REG(0, 0x00)
> +#define ISL7998x_REG_P0_PRODUCT_REV_CODE     ISL7998x_REG(0, 0x01)
> +#define ISL7998x_REG_P0_SW_RESET_CTL         ISL7998x_REG(0, 0x02)
> +#define ISL7998x_REG_P0_IO_BUFFER_CTL                ISL7998x_REG(0, 0x03)
> +#define ISL7998x_REG_P0_IO_BUFFER_CTL_1_1    ISL7998x_REG(0, 0x04)
> +#define ISL7998x_REG_P0_IO_PAD_PULL_EN_CTL   ISL7998x_REG(0, 0x05)
> +#define ISL7998x_REG_P0_IO_BUFFER_CTL_1_2    ISL7998x_REG(0, 0x06)
> +#define ISL7998x_REG_P0_VIDEO_IN_CHAN_CTL    ISL7998x_REG(0, 0x07)
> +#define ISL7998x_REG_P0_CLK_CTL_1            ISL7998x_REG(0, 0x08)
> +#define ISL7998x_REG_P0_CLK_CTL_2            ISL7998x_REG(0, 0x09)
> +#define ISL7998x_REG_P0_CLK_CTL_3            ISL7998x_REG(0, 0x0a)
> +#define ISL7998x_REG_P0_CLK_CTL_4            ISL7998x_REG(0, 0x0b)
> +#define ISL7998x_REG_P0_MPP1_SYNC_CTL                ISL7998x_REG(0, 0x0c)
> +#define ISL7998x_REG_P0_MPP2_SYNC_CTL                ISL7998x_REG(0, 0x0d)
> +#define ISL7998x_REG_P0_IRQ_SYNC_CTL         ISL7998x_REG(0, 0x0e)
> +#define ISL7998x_REG_P0_INTERRUPT_STATUS     ISL7998x_REG(0, 0x10)
> +#define ISL7998x_REG_P0_CHAN_1_IRQ           ISL7998x_REG(0, 0x11)
> +#define ISL7998x_REG_P0_CHAN_2_IRQ           ISL7998x_REG(0, 0x12)
> +#define ISL7998x_REG_P0_CHAN_3_IRQ           ISL7998x_REG(0, 0x13)
> +#define ISL7998x_REG_P0_CHAN_4_IRQ           ISL7998x_REG(0, 0x14)
> +#define ISL7998x_REG_P0_SHORT_DIAG_IRQ               ISL7998x_REG(0, 0x15)
> +#define ISL7998x_REG_P0_CHAN_1_IRQ_EN                ISL7998x_REG(0, 0x16)
> +#define ISL7998x_REG_P0_CHAN_2_IRQ_EN                ISL7998x_REG(0, 0x17)
> +#define ISL7998x_REG_P0_CHAN_3_IRQ_EN                ISL7998x_REG(0, 0x18)
> +#define ISL7998x_REG_P0_CHAN_4_IRQ_EN                ISL7998x_REG(0, 0x19)
> +#define ISL7998x_REG_P0_SHORT_DIAG_IRQ_EN    ISL7998x_REG(0, 0x1a)
> +#define ISL7998x_REG_P0_CHAN_1_STATUS                ISL7998x_REG(0, 0x1b)
> +#define ISL7998x_REG_P0_CHAN_2_STATUS                ISL7998x_REG(0, 0x1c)
> +#define ISL7998x_REG_P0_CHAN_3_STATUS                ISL7998x_REG(0, 0x1d)
> +#define ISL7998x_REG_P0_CHAN_4_STATUS                ISL7998x_REG(0, 0x1e)
> +#define ISL7998x_REG_P0_SHORT_DIAG_STATUS    ISL7998x_REG(0, 0x1f)
> +#define ISL7998x_REG_P0_CLOCK_DELAY          ISL7998x_REG(0, 0x20)
> +
> +#define ISL7998x_REG_Px_DEC_INPUT_FMT(pg)    ISL7998x_REG((pg), 0x02)
> +#define ISL7998x_REG_Px_DEC_STATUS_1(pg)     ISL7998x_REG((pg), 0x03)
> +#define ISL7998x_REG_Px_DEC_HS_DELAY_CTL(pg) ISL7998x_REG((pg), 0x04)
> +#define ISL7998x_REG_Px_DEC_ANCTL(pg)                ISL7998x_REG((pg), 0x06)
> +#define ISL7998x_REG_Px_DEC_CROP_HI(pg)              ISL7998x_REG((pg), 0x07)
> +#define ISL7998x_REG_Px_DEC_VDELAY_LO(pg)    ISL7998x_REG((pg), 0x08)
> +#define ISL7998x_REG_Px_DEC_VACTIVE_LO(pg)   ISL7998x_REG((pg), 0x09)
> +#define ISL7998x_REG_Px_DEC_HDELAY_LO(pg)    ISL7998x_REG((pg), 0x0a)
> +#define ISL7998x_REG_Px_DEC_HACTIVE_LO(pg)   ISL7998x_REG((pg), 0x0b)
> +#define ISL7998x_REG_Px_DEC_CNTRL1(pg)               ISL7998x_REG((pg), 0x0c)
> +#define ISL7998x_REG_Px_DEC_CSC_CTL(pg)              ISL7998x_REG((pg), 0x0d)
> +#define ISL7998x_REG_Px_DEC_BRIGHT(pg)               ISL7998x_REG((pg), 0x10)
> +#define ISL7998x_REG_Px_DEC_CONTRAST(pg)     ISL7998x_REG((pg), 0x11)
> +#define ISL7998x_REG_Px_DEC_SHARPNESS(pg)    ISL7998x_REG((pg), 0x12)
> +#define ISL7998x_REG_Px_DEC_SAT_U(pg)                ISL7998x_REG((pg), 0x13)
> +#define ISL7998x_REG_Px_DEC_SAT_V(pg)                ISL7998x_REG((pg), 0x14)
> +#define ISL7998x_REG_Px_DEC_HUE(pg)          ISL7998x_REG((pg), 0x15)
> +#define ISL7998x_REG_Px_DEC_VERT_PEAK(pg)    ISL7998x_REG((pg), 0x17)
> +#define ISL7998x_REG_Px_DEC_CORING(pg)               ISL7998x_REG((pg), 0x18)
> +#define ISL7998x_REG_Px_DEC_SDT(pg)          ISL7998x_REG((pg), 0x1c)
> +#define ISL7998x_REG_Px_DEC_SDT_DET          BIT(7)
> +#define ISL7998x_REG_Px_DEC_SDTR(pg)         ISL7998x_REG((pg), 0x1d)
> +#define ISL7998x_REG_Px_DEC_CLMPG(pg)                ISL7998x_REG((pg), 0x20)
> +#define ISL7998x_REG_Px_DEC_IAGC(pg)         ISL7998x_REG((pg), 0x21)
> +#define ISL7998x_REG_Px_DEC_AGCGAIN(pg)              ISL7998x_REG((pg), 0x22)
> +#define ISL7998x_REG_Px_DEC_PEAKWT(pg)               ISL7998x_REG((pg), 0x23)
> +#define ISL7998x_REG_Px_DEC_CLMPL(pg)                ISL7998x_REG((pg), 0x24)
> +#define ISL7998x_REG_Px_DEC_SYNCT(pg)                ISL7998x_REG((pg), 0x25)
> +#define ISL7998x_REG_Px_DEC_MISSCNT(pg)              ISL7998x_REG((pg), 0x26)
> +#define ISL7998x_REG_Px_DEC_PCLAMP(pg)               ISL7998x_REG((pg), 0x27)
> +#define ISL7998x_REG_Px_DEC_VERT_CTL_1(pg)   ISL7998x_REG((pg), 0x28)
> +#define ISL7998x_REG_Px_DEC_VERT_CTL_2(pg)   ISL7998x_REG((pg), 0x29)
> +#define ISL7998x_REG_Px_DEC_CLR_KILL_LVL(pg) ISL7998x_REG((pg), 0x2a)
> +#define ISL7998x_REG_Px_DEC_COMB_FILTER_CTL(pg)      ISL7998x_REG((pg), 0x2b)
> +#define ISL7998x_REG_Px_DEC_LUMA_DELAY(pg)   ISL7998x_REG((pg), 0x2c)
> +#define ISL7998x_REG_Px_DEC_MISC1(pg)                ISL7998x_REG((pg), 0x2d)
> +#define ISL7998x_REG_Px_DEC_MISC2(pg)                ISL7998x_REG((pg), 0x2e)
> +#define ISL7998x_REG_Px_DEC_MISC3(pg)                ISL7998x_REG((pg), 0x2f)
> +#define ISL7998x_REG_Px_DEC_MVSN(pg)         ISL7998x_REG((pg), 0x30)
> +#define ISL7998x_REG_Px_DEC_CSTATUS2(pg)     ISL7998x_REG((pg), 0x31)
> +#define ISL7998x_REG_Px_DEC_HFREF(pg)                ISL7998x_REG((pg), 0x32)
> +#define ISL7998x_REG_Px_DEC_CLMD(pg)         ISL7998x_REG((pg), 0x33)
> +#define ISL7998x_REG_Px_DEC_ID_DET_CTL(pg)   ISL7998x_REG((pg), 0x34)
> +#define ISL7998x_REG_Px_DEC_CLCNTL(pg)               ISL7998x_REG((pg), 0x35)
> +#define ISL7998x_REG_Px_DEC_DIFF_CLMP_CTL_1(pg)      ISL7998x_REG((pg), 0x36)
> +#define ISL7998x_REG_Px_DEC_DIFF_CLMP_CTL_2(pg)      ISL7998x_REG((pg), 0x37)
> +#define ISL7998x_REG_Px_DEC_DIFF_CLMP_CTL_3(pg)      ISL7998x_REG((pg), 0x38)
> +#define ISL7998x_REG_Px_DEC_DIFF_CLMP_CTL_4(pg)      ISL7998x_REG((pg), 0x39)
> +#define ISL7998x_REG_Px_DEC_SHORT_DET_CTL(pg)        ISL7998x_REG((pg), 0x3a)
> +#define ISL7998x_REG_Px_DEC_SHORT_DET_CTL_1(pg)      ISL7998x_REG((pg), 0x3b)
> +#define ISL7998x_REG_Px_DEC_AFE_TST_MUX_CTL(pg)      ISL7998x_REG((pg), 0x3c)
> +#define ISL7998x_REG_Px_DEC_DATA_CONV(pg)    ISL7998x_REG((pg), 0x3d)
> +#define ISL7998x_REG_Px_DEC_INTERNAL_TEST(pg)        ISL7998x_REG((pg), 0x3f)
> +#define ISL7998x_REG_Px_DEC_H_DELAY_CTL(pg)  ISL7998x_REG((pg), 0x43)
> +#define ISL7998x_REG_Px_DEC_H_DELAY_II_HI(pg)        ISL7998x_REG((pg), 0x44)
> +#define ISL7998x_REG_Px_DEC_H_DELAY_II_LOW(pg)       ISL7998x_REG((pg), 0x45)
> +
> +#define ISL7998x_REG_Px_ACA_CTL_1(pg)                ISL7998x_REG((pg), 0x80)
> +#define ISL7998x_REG_Px_ACA_GAIN_CTL(pg)     ISL7998x_REG((pg), 0x81)
> +#define ISL7998x_REG_Px_ACA_Y_AVG_HI_LIMIT(pg)       ISL7998x_REG((pg), 0x82)
> +#define ISL7998x_REG_Px_ACA_Y_AVG_LO_LIMIT(pg)       ISL7998x_REG((pg), 0x83)
> +#define ISL7998x_REG_Px_ACA_Y_DET_THRESHOLD(pg)      ISL7998x_REG((pg), 0x84)
> +#define ISL7998x_REG_Px_ACA_BLACK_LVL(pg)    ISL7998x_REG((pg), 0x85)
> +#define ISL7998x_REG_Px_ACA_CENTER_LVL(pg)   ISL7998x_REG((pg), 0x86)
> +#define ISL7998x_REG_Px_ACA_WHITE_LVL(pg)    ISL7998x_REG((pg), 0x87)
> +#define ISL7998x_REG_Px_ACA_MEAN_OFF_LIMIT(pg)       ISL7998x_REG((pg), 0x88)
> +#define ISL7998x_REG_Px_ACA_MEAN_OFF_UPGAIN(pg)      ISL7998x_REG((pg), 0x89)
> +#define ISL7998x_REG_Px_ACA_MEAN_OFF_SLOPE(pg)       ISL7998x_REG((pg), 0x8a)
> +#define ISL7998x_REG_Px_ACA_MEAN_OFF_DNGAIN(pg)      ISL7998x_REG((pg), 0x8b)
> +#define ISL7998x_REG_Px_ACA_DELTA_CO_THRES(pg)       ISL7998x_REG((pg), 0x8c)
> +#define ISL7998x_REG_Px_ACA_DELTA_SLOPE(pg)  ISL7998x_REG((pg), 0x8d)
> +#define ISL7998x_REG_Px_ACA_LO_HI_AVG_THRES(pg)      ISL7998x_REG((pg), 0x8e)
> +#define ISL7998x_REG_Px_ACA_LO_MAX_LVL_CTL(pg)       ISL7998x_REG((pg), 0x8f)
> +#define ISL7998x_REG_Px_ACA_HI_MAX_LVL_CTL(pg)       ISL7998x_REG((pg), 0x90)
> +#define ISL7998x_REG_Px_ACA_LO_UPGAIN_CTL(pg)        ISL7998x_REG((pg), 0x91)
> +#define ISL7998x_REG_Px_ACA_LO_DNGAIN_CTL(pg)        ISL7998x_REG((pg), 0x92)
> +#define ISL7998x_REG_Px_ACA_HI_UPGAIN_CTL(pg)        ISL7998x_REG((pg), 0x93)
> +#define ISL7998x_REG_Px_ACA_HI_DNGAIN_CTL(pg)        ISL7998x_REG((pg), 0x94)
> +#define ISL7998x_REG_Px_ACA_LOPASS_FLT_COEF(pg)      ISL7998x_REG((pg), 0x95)
> +#define ISL7998x_REG_Px_ACA_PDF_INDEX(pg)    ISL7998x_REG((pg), 0x96)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_H_STT(pg)       ISL7998x_REG((pg), 0x97)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_H_SZ1(pg)       ISL7998x_REG((pg), 0x98)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_H_SZ2(pg)       ISL7998x_REG((pg), 0x99)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_V_STT(pg)       ISL7998x_REG((pg), 0x9a)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_V_SZ1(pg)       ISL7998x_REG((pg), 0x9b)
> +#define ISL7998x_REG_Px_ACA_HIST_WIN_V_SZ2(pg)       ISL7998x_REG((pg), 0x9c)
> +#define ISL7998x_REG_Px_ACA_Y_AVG(pg)                ISL7998x_REG((pg), 0xa0)
> +#define ISL7998x_REG_Px_ACA_Y_AVG_LIM(pg)    ISL7998x_REG((pg), 0xa1)
> +#define ISL7998x_REG_Px_ACA_LO_AVG(pg)               ISL7998x_REG((pg), 0xa2)
> +#define ISL7998x_REG_Px_ACA_HI_AVG(pg)               ISL7998x_REG((pg), 0xa3)
> +#define ISL7998x_REG_Px_ACA_Y_MAX(pg)                ISL7998x_REG((pg), 0xa4)
> +#define ISL7998x_REG_Px_ACA_Y_MIN(pg)                ISL7998x_REG((pg), 0xa5)
> +#define ISL7998x_REG_Px_ACA_MOFFSET(pg)              ISL7998x_REG((pg), 0xa6)
> +#define ISL7998x_REG_Px_ACA_LO_GAIN(pg)              ISL7998x_REG((pg), 0xa7)
> +#define ISL7998x_REG_Px_ACA_HI_GAIN(pg)              ISL7998x_REG((pg), 0xa8)
> +#define ISL7998x_REG_Px_ACA_LL_SLOPE(pg)     ISL7998x_REG((pg), 0xa9)
> +#define ISL7998x_REG_Px_ACA_LH_SLOPE(pg)     ISL7998x_REG((pg), 0xaa)
> +#define ISL7998x_REG_Px_ACA_HL_SLOPE(pg)     ISL7998x_REG((pg), 0xab)
> +#define ISL7998x_REG_Px_ACA_HH_SLOPE(pg)     ISL7998x_REG((pg), 0xac)
> +#define ISL7998x_REG_Px_ACA_X_LOW(pg)                ISL7998x_REG((pg), 0xad)
> +#define ISL7998x_REG_Px_ACA_X_MEAN(pg)               ISL7998x_REG((pg), 0xae)
> +#define ISL7998x_REG_Px_ACA_X_HIGH(pg)               ISL7998x_REG((pg), 0xaf)
> +#define ISL7998x_REG_Px_ACA_Y_LOW(pg)                ISL7998x_REG((pg), 0xb0)
> +#define ISL7998x_REG_Px_ACA_Y_MEAN(pg)               ISL7998x_REG((pg), 0xb1)
> +#define ISL7998x_REG_Px_ACA_Y_HIGH(pg)               ISL7998x_REG((pg), 0xb2)
> +#define ISL7998x_REG_Px_ACA_CTL_2(pg)                ISL7998x_REG((pg), 0xb3)
> +#define ISL7998x_REG_Px_ACA_CTL_3(pg)                ISL7998x_REG((pg), 0xb4)
> +#define ISL7998x_REG_Px_ACA_CTL_4(pg)                ISL7998x_REG((pg), 0xb5)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_HIST(pg)        ISL7998x_REG((pg), 0xc0)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TL_H(pg)      ISL7998x_REG((pg), 0xc1)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TL_L(pg)      ISL7998x_REG((pg), 0xc2)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TL_H(pg)      ISL7998x_REG((pg), 0xc3)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TL_L(pg)      ISL7998x_REG((pg), 0xc4)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TR_H(pg)      ISL7998x_REG((pg), 0xc5)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TR_L(pg)      ISL7998x_REG((pg), 0xc6)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TR_H(pg)      ISL7998x_REG((pg), 0xc7)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TR_L(pg)      ISL7998x_REG((pg), 0xc8)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BL_H(pg)      ISL7998x_REG((pg), 0xc9)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BL_L(pg)      ISL7998x_REG((pg), 0xca)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BL_H(pg)      ISL7998x_REG((pg), 0xcb)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BL_L(pg)      ISL7998x_REG((pg), 0xcc)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BR_H(pg)      ISL7998x_REG((pg), 0xcd)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BR_L(pg)      ISL7998x_REG((pg), 0xce)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BR_H(pg)      ISL7998x_REG((pg), 0xcf)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BR_L(pg)      ISL7998x_REG((pg), 0xd0)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_LM_H(pg)      ISL7998x_REG((pg), 0xd1)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_LM_L(pg)      ISL7998x_REG((pg), 0xd2)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_LM_H(pg)      ISL7998x_REG((pg), 0xd3)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_LM_L(pg)      ISL7998x_REG((pg), 0xd4)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TM_H(pg)      ISL7998x_REG((pg), 0xd5)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_TM_L(pg)      ISL7998x_REG((pg), 0xd6)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TM_H(pg)      ISL7998x_REG((pg), 0xd7)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_TM_L(pg)      ISL7998x_REG((pg), 0xd8)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BM_H(pg)      ISL7998x_REG((pg), 0xd9)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_BM_L(pg)      ISL7998x_REG((pg), 0xda)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BM_H(pg)      ISL7998x_REG((pg), 0xdb)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_BM_L(pg)      ISL7998x_REG((pg), 0xdc)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_RM_H(pg)      ISL7998x_REG((pg), 0xdd)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_X_RM_L(pg)      ISL7998x_REG((pg), 0xde)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_RM_H(pg)      ISL7998x_REG((pg), 0xdf)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_RM_L(pg)      ISL7998x_REG((pg), 0xe0)
> +#define ISL7998x_REG_Px_ACA_HIST_DATA_LO(pg) ISL7998x_REG((pg), 0xe1)
> +#define ISL7998x_REG_Px_ACA_HIST_DATA_MID(pg)        ISL7998x_REG((pg), 0xe2)
> +#define ISL7998x_REG_Px_ACA_HIST_DATA_HI(pg) ISL7998x_REG((pg), 0xe3)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_Y_CLR(pg)       ISL7998x_REG((pg), 0xe4)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_CB_CLR(pg)      ISL7998x_REG((pg), 0xe5)
> +#define ISL7998x_REG_Px_ACA_FLEX_WIN_CR_CLR(pg)      ISL7998x_REG((pg), 0xe6)
> +#define ISL7998x_REG_Px_ACA_XFER_HIST_HOST(pg)       ISL7998x_REG((pg), 0xe7)
> +
> +#define ISL7998x_REG_P5_LI_ENGINE_CTL                ISL7998x_REG(5, 0x00)
> +#define ISL7998x_REG_P5_LI_ENGINE_LINE_CTL   ISL7998x_REG(5, 0x01)
> +#define ISL7998x_REG_P5_LI_ENGINE_PIC_WIDTH  ISL7998x_REG(5, 0x02)
> +#define ISL7998x_REG_P5_LI_ENGINE_SYNC_CTL   ISL7998x_REG(5, 0x03)
> +#define ISL7998x_REG_P5_LI_ENGINE_VC_ASSIGNMENT      ISL7998x_REG(5, 0x04)
> +#define ISL7998x_REG_P5_LI_ENGINE_TYPE_CTL   ISL7998x_REG(5, 0x05)
> +#define ISL7998x_REG_P5_LI_ENGINE_FIFO_CTL   ISL7998x_REG(5, 0x06)
> +#define ISL7998x_REG_P5_MIPI_READ_START_CTL  ISL7998x_REG(5, 0x07)
> +#define ISL7998x_REG_P5_PSEUDO_FRM_FIELD_CTL ISL7998x_REG(5, 0x08)
> +#define ISL7998x_REG_P5_ONE_FIELD_MODE_CTL   ISL7998x_REG(5, 0x09)
> +#define ISL7998x_REG_P5_MIPI_INT_HW_TST_CTR  ISL7998x_REG(5, 0x0a)
> +#define ISL7998x_REG_P5_TP_GEN_BAR_PATTERN   ISL7998x_REG(5, 0x0b)
> +#define ISL7998x_REG_P5_MIPI_PCNT_PSFRM              ISL7998x_REG(5, 0x0c)
> +#define ISL7998x_REG_P5_LI_ENGINE_TP_GEN_CTL ISL7998x_REG(5, 0x0d)
> +#define ISL7998x_REG_P5_MIPI_VBLANK_PSFRM    ISL7998x_REG(5, 0x0e)
> +#define ISL7998x_REG_P5_LI_ENGINE_CTL_2              ISL7998x_REG(5, 0x0f)
> +#define ISL7998x_REG_P5_MIPI_WCNT_1          ISL7998x_REG(5, 0x10)
> +#define ISL7998x_REG_P5_MIPI_WCNT_2          ISL7998x_REG(5, 0x11)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_1       ISL7998x_REG(5, 0x12)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_2       ISL7998x_REG(5, 0x13)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_3       ISL7998x_REG(5, 0x14)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_4       ISL7998x_REG(5, 0x15)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_5       ISL7998x_REG(5, 0x16)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_6       ISL7998x_REG(5, 0x17)
> +#define ISL7998x_REG_P5_MIPI_DPHY_PARAMS_1   ISL7998x_REG(5, 0x18)
> +#define ISL7998x_REG_P5_MIPI_DPHY_SOT_PERIOD ISL7998x_REG(5, 0x19)
> +#define ISL7998x_REG_P5_MIPI_DPHY_EOT_PERIOD ISL7998x_REG(5, 0x1a)
> +#define ISL7998x_REG_P5_MIPI_DPHY_PARAMS_2   ISL7998x_REG(5, 0x1b)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_7       ISL7998x_REG(5, 0x1c)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_8       ISL7998x_REG(5, 0x1d)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_9       ISL7998x_REG(5, 0x1e)
> +#define ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_10      ISL7998x_REG(5, 0x1f)
> +#define ISL7998x_REG_P5_TP_GEN_MIPI          ISL7998x_REG(5, 0x20)
> +#define ISL7998x_REG_P5_ESC_MODE_TIME_CTL    ISL7998x_REG(5, 0x21)
> +#define ISL7998x_REG_P5_AUTO_TEST_ERR_DET    ISL7998x_REG(5, 0x22)
> +#define ISL7998x_REG_P5_MIPI_TIMING          ISL7998x_REG(5, 0x23)
> +#define ISL7998x_REG_P5_PIC_HEIGHT_HIGH              ISL7998x_REG(5, 0x24)
> +#define ISL7998x_REG_P5_PIC_HEIGHT_LOW               ISL7998x_REG(5, 0x25)
> +#define ISL7998x_REG_P5_MIPI_SP_HS_TRL_CTL   ISL7998x_REG(5, 0x26)
> +#define ISL7998x_REG_P5_FIFO_THRSH_CNT_1     ISL7998x_REG(5, 0x28)
> +#define ISL7998x_REG_P5_FIFO_THRSH_CNT_2     ISL7998x_REG(5, 0x29)
> +#define ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_1        ISL7998x_REG(5, 0x2a)
> +#define ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_2        ISL7998x_REG(5, 0x2b)
> +#define ISL7998x_REG_P5_PSF_FIELD_END_CTL_1  ISL7998x_REG(5, 0x2c)
> +#define ISL7998x_REG_P5_PSF_FIELD_END_CTL_2  ISL7998x_REG(5, 0x2d)
> +#define ISL7998x_REG_P5_PSF_FIELD_END_CTL_3  ISL7998x_REG(5, 0x2e)
> +#define ISL7998x_REG_P5_PSF_FIELD_END_CTL_4  ISL7998x_REG(5, 0x2f)
> +#define ISL7998x_REG_P5_MIPI_ANA_DATA_CTL_1  ISL7998x_REG(5, 0x30)
> +#define ISL7998x_REG_P5_MIPI_ANA_DATA_CTL_2  ISL7998x_REG(5, 0x31)
> +#define ISL7998x_REG_P5_MIPI_ANA_CLK_CTL     ISL7998x_REG(5, 0x32)
> +#define ISL7998x_REG_P5_PLL_ANA_STATUS               ISL7998x_REG(5, 0x33)
> +#define ISL7998x_REG_P5_PLL_ANA_MISC_CTL     ISL7998x_REG(5, 0x34)
> +#define ISL7998x_REG_P5_MIPI_ANA             ISL7998x_REG(5, 0x35)
> +#define ISL7998x_REG_P5_PLL_ANA                      ISL7998x_REG(5, 0x36)
> +#define ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_1  ISL7998x_REG(5, 0x38)
> +#define ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_2  ISL7998x_REG(5, 0x39)
> +#define ISL7998x_REG_P5_H_LINE_CNT_1         ISL7998x_REG(5, 0x3a)
> +#define ISL7998x_REG_P5_H_LINE_CNT_2         ISL7998x_REG(5, 0x3b)
> +#define ISL7998x_REG_P5_HIST_LINE_CNT_1              ISL7998x_REG(5, 0x3c)
> +#define ISL7998x_REG_P5_HIST_LINE_CNT_2              ISL7998x_REG(5, 0x3d)
> +
> +static const struct reg_sequence isl7998x_init_seq_1[] = {
> +     { ISL7998x_REG_P0_SHORT_DIAG_IRQ_EN, 0xff },
> +     { ISL7998x_REG_Px_DEC_SDT(0x1), 0x07 },
> +     { ISL7998x_REG_Px_DEC_SHORT_DET_CTL_1(0x1), 0x03 },
> +     { ISL7998x_REG_Px_DEC_SDT(0x2), 0x07 },
> +     { ISL7998x_REG_Px_DEC_SHORT_DET_CTL_1(0x2), 0x03 },
> +     { ISL7998x_REG_Px_DEC_SDT(0x3), 0x07 },
> +     { ISL7998x_REG_Px_DEC_SHORT_DET_CTL_1(0x3), 0x03 },
> +     { ISL7998x_REG_Px_DEC_SDT(0x4), 0x07 },
> +     { ISL7998x_REG_Px_DEC_SHORT_DET_CTL_1(0x4), 0x03 },
> +     { ISL7998x_REG_P5_LI_ENGINE_CTL, 0x00 },
> +     { ISL7998x_REG_P0_SW_RESET_CTL, 0x1f, 10 },
> +     { ISL7998x_REG_P0_IO_BUFFER_CTL, 0x00 },
> +     { ISL7998x_REG_P0_MPP2_SYNC_CTL, 0xc9 },
> +     { ISL7998x_REG_P0_IRQ_SYNC_CTL, 0xc9 },
> +     { ISL7998x_REG_P0_CHAN_1_IRQ, 0x03 },
> +     { ISL7998x_REG_P0_CHAN_2_IRQ, 0x00 },
> +     { ISL7998x_REG_P0_CHAN_3_IRQ, 0x00 },
> +     { ISL7998x_REG_P0_CHAN_4_IRQ, 0x00 },
> +     { ISL7998x_REG_P5_LI_ENGINE_CTL, 0x02 },
> +     { ISL7998x_REG_P5_LI_ENGINE_LINE_CTL, 0x85 },
> +     { ISL7998x_REG_P5_LI_ENGINE_PIC_WIDTH, 0xa0 },
> +     { ISL7998x_REG_P5_LI_ENGINE_SYNC_CTL, 0x18 },
> +     { ISL7998x_REG_P5_LI_ENGINE_TYPE_CTL, 0x40 },
> +     { ISL7998x_REG_P5_LI_ENGINE_FIFO_CTL, 0x40 },
> +     { ISL7998x_REG_P5_MIPI_WCNT_1, 0x05 },
> +     { ISL7998x_REG_P5_MIPI_WCNT_2, 0xa0 },
> +     { ISL7998x_REG_P5_TP_GEN_MIPI, 0x00 },
> +     { ISL7998x_REG_P5_ESC_MODE_TIME_CTL, 0x0c },
> +     { ISL7998x_REG_P5_MIPI_SP_HS_TRL_CTL, 0x00 },
> +     { ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_1, 0x00 },
> +     { ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_2, 0x19 },
> +     { ISL7998x_REG_P5_PSF_FIELD_END_CTL_1, 0x18 },
> +     { ISL7998x_REG_P5_PSF_FIELD_END_CTL_2, 0xf1 },
> +     { ISL7998x_REG_P5_PSF_FIELD_END_CTL_3, 0x00 },
> +     { ISL7998x_REG_P5_PSF_FIELD_END_CTL_4, 0xf1 },
> +     { ISL7998x_REG_P5_MIPI_ANA_DATA_CTL_1, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_ANA_DATA_CTL_2, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_ANA_CLK_CTL, 0x00 },
> +     { ISL7998x_REG_P5_PLL_ANA_STATUS, 0xc0 },
> +     { ISL7998x_REG_P5_PLL_ANA_MISC_CTL, 0x18 },
> +     { ISL7998x_REG_P5_PLL_ANA, 0x00 },
> +     { ISL7998x_REG_P0_SW_RESET_CTL, 0x10, 10 },
> +     /* Page 0xf means write to all of pages 1,2,3,4 */
> +     { ISL7998x_REG_Px_DEC_VDELAY_LO(0xf), 0x14 },
> +     { ISL7998x_REG_Px_DEC_MISC3(0xf), 0xe6 },
> +     { ISL7998x_REG_Px_DEC_CLMD(0xf), 0x85 },
> +     { ISL7998x_REG_Px_DEC_H_DELAY_II_LOW(0xf), 0x11 },
> +     { ISL7998x_REG_Px_ACA_XFER_HIST_HOST(0xf), 0x00 },
> +     { ISL7998x_REG_P0_CLK_CTL_1, 0x1f },
> +     { ISL7998x_REG_P0_CLK_CTL_2, 0x43 },
> +     { ISL7998x_REG_P0_CLK_CTL_3, 0x4f },

It'd be great to see what these magical numbers signify. How about some
additional #defines for the bits? Same below.

> +};
> +
> +static const struct reg_sequence isl7998x_init_seq_2[] = {
> +     { ISL7998x_REG_P5_LI_ENGINE_SYNC_CTL, 0x10 },
> +     { ISL7998x_REG_P5_LI_ENGINE_VC_ASSIGNMENT, 0xe4 },
> +     { ISL7998x_REG_P5_LI_ENGINE_TYPE_CTL, 0x00 },
> +     { ISL7998x_REG_P5_LI_ENGINE_FIFO_CTL, 0x60 },
> +     { ISL7998x_REG_P5_MIPI_READ_START_CTL, 0x2b },
> +     { ISL7998x_REG_P5_PSEUDO_FRM_FIELD_CTL, 0x02 },
> +     { ISL7998x_REG_P5_ONE_FIELD_MODE_CTL, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_INT_HW_TST_CTR, 0x62 },
> +     { ISL7998x_REG_P5_TP_GEN_BAR_PATTERN, 0x02 },
> +     { ISL7998x_REG_P5_MIPI_PCNT_PSFRM, 0x36 },
> +     { ISL7998x_REG_P5_LI_ENGINE_TP_GEN_CTL, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_VBLANK_PSFRM, 0x6c },
> +     { ISL7998x_REG_P5_LI_ENGINE_CTL_2, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_WCNT_1, 0x05 },
> +     { ISL7998x_REG_P5_MIPI_WCNT_2, 0xa0 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_1, 0x77 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_2, 0x17 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_3, 0x08 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_4, 0x38 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_5, 0x14 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_6, 0xf6 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_PARAMS_1, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_SOT_PERIOD, 0x17 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_EOT_PERIOD, 0x0a },
> +     { ISL7998x_REG_P5_MIPI_DPHY_PARAMS_2, 0x71 },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_7, 0x7a },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_8, 0x0f },
> +     { ISL7998x_REG_P5_MIPI_DPHY_TIMING_CTL_9, 0x8c },
> +     { ISL7998x_REG_P5_MIPI_SP_HS_TRL_CTL, 0x08 },
> +     { ISL7998x_REG_P5_FIFO_THRSH_CNT_1, 0x01 },
> +     { ISL7998x_REG_P5_FIFO_THRSH_CNT_2, 0x0e },
> +     { ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_1, 0x00 },
> +     { ISL7998x_REG_P5_TP_GEN_RND_SYNC_CTL_2, 0x00 },
> +     { ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_1, 0x03 },
> +     { ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_2, 0xc0 },
> +     { ISL7998x_REG_P5_H_LINE_CNT_1, 0x06 },
> +     { ISL7998x_REG_P5_H_LINE_CNT_2, 0xb3 },
> +     { ISL7998x_REG_P5_HIST_LINE_CNT_1, 0x00 },
> +     { ISL7998x_REG_P5_HIST_LINE_CNT_2, 0xf1 },
> +     { ISL7998x_REG_P5_LI_ENGINE_FIFO_CTL, 0x00 },
> +     { ISL7998x_REG_P5_MIPI_ANA, 0x00 },
> +     /*
> +      * Wait a bit after reset so that the chip can capture a frame
> +      * and update internal line counters.
> +      */
> +     { ISL7998x_REG_P0_SW_RESET_CTL, 0x00, 50 },
> +};
> +
> +struct isl7998x_datafmt {
> +     u32                     code;
> +     enum v4l2_colorspace    colorspace;
> +};
> +
> +static const struct isl7998x_datafmt isl7998x_colour_fmts[] = {
> +     { MEDIA_BUS_FMT_YUYV8_2X8, V4L2_COLORSPACE_SRGB },
> +};
> +
> +/* Menu items for LINK_FREQ V4L2 control */
> +static const s64 link_freq_menu_items[] = {
> +     108000000, 216000000, 432000000
> +};

Where to these numbers come from?

> +
> +/* Menu items for TEST_PATTERN V4L2 control */
> +static const char * const isl7998x_test_pattern_menu[] = {
> +     "Disabled", "Enabled-PAL (720x576)", "Enabled-NTSC (720x480)"
> +};
> +
> +struct isl7998x {
> +     struct v4l2_subdev              subdev;
> +     struct regmap                   *regmap;
> +     struct gpio_desc                *pd_gpio;
> +     unsigned int                    nr_mipi_lanes;
> +     u32                             nr_inputs;
> +
> +     unsigned int                    width;
> +     unsigned int                    height;
> +     const struct isl7998x_datafmt   *fmt;
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +     struct media_pad                pad;

Hmm. Didn't you have four inputs in your device?

> +#endif
> +
> +     struct v4l2_ctrl_handler        ctrl_handler;
> +     struct mutex                    ctrl_mutex;
> +     /* V4L2 Controls */
> +     struct v4l2_ctrl                *link_freq;
> +     u8                              test_pattern_enabled;
> +     u8                              test_pattern_bars;
> +     u8                              test_pattern_chans;
> +     u8                              test_pattern_color;
> +};
> +
> +static struct isl7998x *sd_to_isl7998x(struct v4l2_subdev *sd)
> +{
> +     return container_of(sd, struct isl7998x, subdev);
> +}
> +
> +static struct isl7998x *i2c_to_isl7998x(const struct i2c_client *client)
> +{
> +     return sd_to_isl7998x(i2c_get_clientdata(client));
> +}
> +
> +static int isl7998x_init(struct isl7998x *isl7998x)
> +{
> +     const unsigned int lanes = isl7998x->nr_mipi_lanes;
> +     const u32 isl7998x_video_in_chan_map[] = { 0x00, 0x11, 0x02, 0x02 };
> +     const struct reg_sequence isl7998x_init_seq_custom[] = {
> +             { ISL7998x_REG_P0_VIDEO_IN_CHAN_CTL,
> +               isl7998x_video_in_chan_map[isl7998x->nr_inputs - 1] },
> +             { ISL7998x_REG_P0_CLK_CTL_4, (lanes == 1) ? 0x40 : 0x41 },
> +             { ISL7998x_REG_P5_LI_ENGINE_CTL, (lanes == 1) ? 0x01 : 0x02 },
> +             { ISL7998x_REG_P5_LI_ENGINE_LINE_CTL,
> +               0x20 | ((isl7998x->width >> 7) & 0x1f) },
> +             { ISL7998x_REG_P5_LI_ENGINE_PIC_WIDTH,
> +               (isl7998x->width << 1) & 0xff },
> +     };
> +     struct regmap *regmap = isl7998x->regmap;
> +     int ret;
> +
> +     ret = regmap_register_patch(regmap, isl7998x_init_seq_1,
> +                                   ARRAY_SIZE(isl7998x_init_seq_1));
> +     if (ret)
> +             return ret;
> +
> +     ret = regmap_register_patch(regmap, isl7998x_init_seq_custom,
> +                                   ARRAY_SIZE(isl7998x_init_seq_custom));
> +     if (ret)
> +             return ret;
> +
> +     return regmap_register_patch(regmap, isl7998x_init_seq_2,
> +                                   ARRAY_SIZE(isl7998x_init_seq_2));
> +}
> +
> +static int isl7998x_g_mbus_config(struct v4l2_subdev *sd,
> +                               struct v4l2_mbus_config *cfg)
> +{
> +     struct isl7998x *isl7998x = sd_to_isl7998x(sd);
> +
> +     cfg->type = V4L2_MBUS_CSI2_DPHY;
> +     cfg->flags = V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
> +     if (isl7998x->nr_mipi_lanes == 1)
> +             cfg->flags |= V4L2_MBUS_CSI2_1_LANE;
> +     else
> +             cfg->flags |= V4L2_MBUS_CSI2_2_LANE;

Drivers nowadays generally get this from DT. You can omit this function
safely. For dynamic configuration we'll need something else (Jacopo's been
working on that with me).

> +
> +     return 0;
> +}
> +
> +static int isl7998x_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +     struct isl7998x *isl7998x = sd_to_isl7998x(sd);
> +
> +     return isl7998x_init(isl7998x);

Is this needed both to initialise the hardware as well as start streaming?
Does this also enable the CSI-2 transmitter in driver's probe? This could
be problematic for some receivers.

> +}
> +
> +static int isl7998x_enum_mbus_code(struct v4l2_subdev *sd,
> +                                struct v4l2_subdev_pad_config *cfg,
> +                                struct v4l2_subdev_mbus_code_enum *code)
> +{
> +     if (code->pad || code->index >= ARRAY_SIZE(isl7998x_colour_fmts))
> +             return -EINVAL;
> +
> +     code->code = isl7998x_colour_fmts[code->index].code;

A newline would be nice here.

> +     return 0;
> +}
> +
> +static const unsigned int isl7998x_std_res[] = {
> +     480, 576, 576, 480, 480, 576, 480, 480
> +};
> +
> +static int isl7998x_update_std(struct isl7998x *isl7998x)
> +{
> +     unsigned int height[ISL7998x_INPUTS];
> +     u8 scanning = GENMASK(ISL7998x_INPUTS - 1, 0);
> +     unsigned int i;
> +     int ret;
> +     u32 reg;
> +
> +     while (true) {
> +             for (i = 0; i < ISL7998x_INPUTS; i++) {
> +                     ret = regmap_read(isl7998x->regmap,
> +                                       ISL7998x_REG_Px_DEC_SDT(i + 1), &reg);
> +                     if (ret)
> +                             return ret;
> +
> +                     /* Detection is still in progress, restart. */
> +                     if (reg & ISL7998x_REG_Px_DEC_SDT_DET) {
> +                             scanning = GENMASK(ISL7998x_INPUTS - 1, 0);
> +                             break;
> +                     }
> +
> +                     scanning &= ~BIT(i);
> +                     height[i] = isl7998x_std_res[(reg >> 4) & 0x7];
> +             }
> +
> +             if (!scanning)
> +                     break;
> +
> +             mdelay(1);

How long does this take in general? Could you use msleep() instead of
mdelay() in order to avoid a busy loop at least seemingly of unknown
length?

> +     }
> +
> +     /*
> +      * According to Renesas FAE, all input cameras must have the
> +      * same standard on this chip.
> +      */
> +     for (i = 1; i < isl7998x->nr_inputs ; i++)
> +             if (height[i - 1] != height[i])
> +                     return -EINVAL;
> +
> +     isl7998x->height = height[0];
> +
> +     return 0;
> +}
> +
> +static int isl7998x_get_fmt(struct v4l2_subdev *sd,
> +                         struct v4l2_subdev_pad_config *cfg,
> +                         struct v4l2_subdev_format *format)
> +{
> +     struct isl7998x *isl7998x = sd_to_isl7998x(sd);
> +     struct v4l2_mbus_framefmt *mf = &format->format;
> +
> +     if (format->pad != 0)
> +             return -EINVAL;
> +
> +     if (isl7998x->test_pattern_enabled == 1) {
> +             mf->width       = 720;
> +             mf->height      = 576;
> +     } else if (isl7998x->test_pattern_enabled == 2) {
> +             mf->width       = 720;
> +             mf->height      = 480;
> +     } else {
> +             mf->width       = isl7998x->width;
> +             mf->height      = isl7998x->height;
> +     }
> +
> +     mf->code        = isl7998x->fmt->code;
> +     mf->field       = V4L2_FIELD_INTERLACED;
> +     mf->colorspace  = 0;
> +
> +     return 0;
> +}
> +
> +static int isl7998x_set_fmt(struct v4l2_subdev *sd,
> +             struct v4l2_subdev_pad_config *cfg,
> +             struct v4l2_subdev_format *format)
> +{
> +     struct isl7998x *isl7998x = sd_to_isl7998x(sd);
> +     struct v4l2_mbus_framefmt *mf = &format->format;
> +     int ret;
> +
> +     if (format->pad != 0)
> +             return -EINVAL;

You can omit the pad checks in pad ops; the framework does that nowadays.

> +
> +     if (format->format.width != 720 ||
> +         (format->format.height != 480 && format->format.height != 576))
> +             return -EINVAL;
> +
> +     if (format->format.code != MEDIA_BUS_FMT_YUYV8_2X8)
> +             return -EINVAL;

Instead of returning an error, you should simply pick a valid format if the
user-supplied format (mbus code, size) isn't supported.

> +
> +     mf->width       = format->format.width;
> +     mf->height      = format->format.height;
> +     mf->code        = format->format.code;
> +     mf->field       = V4L2_FIELD_INTERLACED;
> +     mf->colorspace  = 0;

I'd just use what the user provided.

> +
> +     if (format->which != V4L2_SUBDEV_FORMAT_TRY) {
> +             ret = isl7998x_update_std(isl7998x);
> +             if (ret)
> +                     return ret;
> +             mf->width = isl7998x->width;
> +             mf->height = isl7998x->height;
> +             isl7998x->fmt = &isl7998x_colour_fmts[0];
> +     }
> +
> +     return 0;
> +}
> +
> +static int isl7998x_set_test_pattern(struct isl7998x *isl7998x)
> +{
> +     const struct reg_sequence isl7998x_init_seq_tpg_off[] = {
> +             { ISL7998x_REG_P5_LI_ENGINE_TP_GEN_CTL, 0 },
> +             { ISL7998x_REG_P5_LI_ENGINE_CTL_2, 0 }
> +     };
> +     const struct reg_sequence isl7998x_init_seq_tpg_on[] = {
> +             { ISL7998x_REG_P5_TP_GEN_BAR_PATTERN,
> +               isl7998x->test_pattern_bars << 6 },
> +             { ISL7998x_REG_P5_LI_ENGINE_CTL_2,
> +               isl7998x->test_pattern_enabled == 1 ? BIT(2) : 0 },
> +             { ISL7998x_REG_P5_LI_ENGINE_TP_GEN_CTL,
> +               (isl7998x->test_pattern_chans << 4) |
> +               (isl7998x->test_pattern_color << 2) }
> +     };
> +     struct regmap *regmap = isl7998x->regmap;
> +
> +     if (isl7998x->test_pattern_enabled) {
> +             return regmap_register_patch(regmap, isl7998x_init_seq_tpg_on,
> +                                     ARRAY_SIZE(isl7998x_init_seq_tpg_on));
> +     } else {
> +             return regmap_register_patch(regmap, isl7998x_init_seq_tpg_off,
> +                                     ARRAY_SIZE(isl7998x_init_seq_tpg_off));
> +     }

No need for braces.

> +}
> +
> +static int isl7998x_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +     struct isl7998x *isl7998x = container_of(ctrl->handler,
> +                                            struct isl7998x, ctrl_handler);
> +
> +     switch (ctrl->id) {
> +     case V4L2_CID_TEST_PATTERN_BARS:
> +             isl7998x->test_pattern_bars = ctrl->val & 0x3;
> +             return isl7998x_set_test_pattern(isl7998x);
> +     case V4L2_CID_TEST_PATTERN_CHANNELS:
> +             isl7998x->test_pattern_chans = ctrl->val & 0xf;
> +             return isl7998x_set_test_pattern(isl7998x);
> +     case V4L2_CID_TEST_PATTERN_COLOR:
> +             isl7998x->test_pattern_color = ctrl->val & 0x3;
> +             return isl7998x_set_test_pattern(isl7998x);
> +     case V4L2_CID_TEST_PATTERN:
> +             isl7998x->test_pattern_enabled = !!ctrl->val;
> +             return isl7998x_set_test_pattern(isl7998x);

It'd simplify the driver to use the control value in
isl7998x_set_test_pattern() without storing the intermediate result in
driver's own struct.

> +     }
> +
> +     return 0;
> +}
> +
> +static int isl7998x_get_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +     struct isl7998x *isl7998x = container_of(ctrl->handler,
> +                                            struct isl7998x, ctrl_handler);
> +
> +     v4l2_info(&isl7998x->subdev, "ctrl(id:0x%x,val:0x%x) is not handled\n",
> +               ctrl->id, ctrl->val);

If you have no volatile controls, you can omit this function.

> +
> +     return 0;
> +}
> +
> +static const struct v4l2_subdev_video_ops isl7998x_subdev_video_ops = {
> +     .g_mbus_config  = isl7998x_g_mbus_config,
> +     .s_stream       = isl7998x_s_stream,
> +};
> +
> +static const struct v4l2_subdev_pad_ops isl7998x_subdev_pad_ops = {
> +     .enum_mbus_code = isl7998x_enum_mbus_code,
> +     .get_fmt        = isl7998x_get_fmt,
> +     .set_fmt        = isl7998x_set_fmt,
> +};
> +
> +static const struct v4l2_subdev_ops isl7998x_subdev_ops = {
> +     .video          = &isl7998x_subdev_video_ops,
> +     .pad            = &isl7998x_subdev_pad_ops,
> +};
> +
> +static const struct media_entity_operations isl7998x_entity_ops = {
> +     .link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static const struct v4l2_ctrl_ops isl7998x_ctrl_ops = {
> +     .s_ctrl                 = isl7998x_set_ctrl,
> +     .g_volatile_ctrl        = isl7998x_get_ctrl,
> +};
> +
> +static const char * const isl7998x_test_pattern_bars[] = {
> +     "bbbbwb", "bbbwwb", "bbwbwb", "bbwwwb"
> +};
> +
> +static const char * const isl7998x_test_pattern_colors[] = {
> +     "Yellow", "Blue", "Green", "Pink"
> +};
> +
> +static const struct v4l2_ctrl_config isl7998x_ctrls[] = {
> +     {
> +             .ops            = &isl7998x_ctrl_ops,
> +             .id             = V4L2_CID_TEST_PATTERN_BARS,
> +             .type           = V4L2_CTRL_TYPE_MENU,
> +             .name           = "Test Pattern Bars",
> +             .max            = ARRAY_SIZE(isl7998x_test_pattern_bars) - 1,
> +             .def            = 0,
> +             .qmenu          = isl7998x_test_pattern_bars,
> +     }, {
> +             .ops            = &isl7998x_ctrl_ops,
> +             .id             = V4L2_CID_TEST_PATTERN_CHANNELS,
> +             .type           = V4L2_CTRL_TYPE_INTEGER,
> +             .name           = "Test Pattern Channels",
> +             .min            = 0,
> +             .max            = 0xf,
> +             .step           = 1,
> +             .def            = 0,
> +             .flags          = 0,
> +     }, {
> +             .ops            = &isl7998x_ctrl_ops,
> +             .id             = V4L2_CID_TEST_PATTERN_COLOR,
> +             .type           = V4L2_CTRL_TYPE_MENU,
> +             .name           = "Test Pattern Color",
> +             .max            = ARRAY_SIZE(isl7998x_test_pattern_colors) - 1,
> +             .def            = 0,
> +             .qmenu          = isl7998x_test_pattern_colors,
> +     },
> +};
> +
> +#define ISL7998x_REG_DECODER_ACA_READABLE_RANGE(page)                        
> \
> +     /* Decoder range */                                             \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_INPUT_FMT(page),           \
> +                      ISL7998x_REG_Px_DEC_HS_DELAY_CTL(page)),       \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_ANCTL(page),               \
> +                      ISL7998x_REG_Px_DEC_CSC_CTL(page)),            \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_BRIGHT(page),              \
> +                      ISL7998x_REG_Px_DEC_HUE(page)),                \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_VERT_PEAK(page),           \
> +                      ISL7998x_REG_Px_DEC_CORING(page)),             \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_SDT(page),                 \
> +                      ISL7998x_REG_Px_DEC_SDTR(page)),               \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_CLMPG(page),               \
> +                      ISL7998x_REG_Px_DEC_DATA_CONV(page)),          \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_INTERNAL_TEST(page),       \
> +                      ISL7998x_REG_Px_DEC_INTERNAL_TEST(page)),      \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_H_DELAY_CTL(page),         \
> +                      ISL7998x_REG_Px_DEC_H_DELAY_II_LOW(page)),     \
> +     /* ACA range */                                                 \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_CTL_1(page),               \
> +                      ISL7998x_REG_Px_ACA_HIST_WIN_V_SZ2(page)),     \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_Y_AVG(page),               \
> +                      ISL7998x_REG_Px_ACA_CTL_4(page)),              \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_FLEX_WIN_HIST(page),       \
> +                      ISL7998x_REG_Px_ACA_XFER_HIST_HOST(page)),     \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(page),                \
> +                      ISL7998x_REG_Px_DEC_PAGE(page))
> +
> +#define ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(page)                       
> \
> +     /* Decoder range */                                             \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_INPUT_FMT(page),           \
> +                      ISL7998x_REG_Px_DEC_INPUT_FMT(page)),          \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_HS_DELAY_CTL(page),        \
> +                      ISL7998x_REG_Px_DEC_HS_DELAY_CTL(page)),       \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_ANCTL(page),               \
> +                      ISL7998x_REG_Px_DEC_CSC_CTL(page)),            \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_BRIGHT(page),              \
> +                      ISL7998x_REG_Px_DEC_HUE(page)),                \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_VERT_PEAK(page),           \
> +                      ISL7998x_REG_Px_DEC_CORING(page)),             \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_SDT(page),                 \
> +                      ISL7998x_REG_Px_DEC_SDTR(page)),               \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_CLMPG(page),               \
> +                      ISL7998x_REG_Px_DEC_MISC3(page)),              \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_CLMD(page),                \
> +                      ISL7998x_REG_Px_DEC_DATA_CONV(page)),          \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_INTERNAL_TEST(page),       \
> +                      ISL7998x_REG_Px_DEC_INTERNAL_TEST(page)),      \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_H_DELAY_CTL(page),         \
> +                      ISL7998x_REG_Px_DEC_H_DELAY_II_LOW(page)),     \
> +     /* ACA range */                                                 \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_CTL_1(page),               \
> +                      ISL7998x_REG_Px_ACA_HIST_WIN_V_SZ2(page)),     \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_CTL_2(page),               \
> +                      ISL7998x_REG_Px_ACA_CTL_4(page)),              \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_FLEX_WIN_HIST(page),       \
> +                      ISL7998x_REG_Px_ACA_HIST_DATA_LO(page)),       \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_XFER_HIST_HOST(page),      \
> +                      ISL7998x_REG_Px_ACA_XFER_HIST_HOST(page)),     \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(page),                \
> +                      ISL7998x_REG_Px_DEC_PAGE(page))
> +
> +#define ISL7998x_REG_DECODER_ACA_VOLATILE_RANGE(page)                        
> \
> +     /* Decoder range */                                             \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_STATUS_1(page),            \
> +                      ISL7998x_REG_Px_DEC_STATUS_1(page)),           \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_SDT(page),                 \
> +                      ISL7998x_REG_Px_DEC_SDT(page)),                \
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_MVSN(page),                \
> +                      ISL7998x_REG_Px_DEC_HFREF(page)),              \
> +     /* ACA range */                                                 \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_Y_AVG(page),               \
> +                      ISL7998x_REG_Px_ACA_Y_HIGH(page)),             \
> +     regmap_reg_range(ISL7998x_REG_Px_ACA_HIST_DATA_LO(page),        \
> +                      ISL7998x_REG_Px_ACA_FLEX_WIN_CR_CLR(page))
> +
> +static const struct regmap_range isl7998x_readable_ranges[] = {
> +     regmap_reg_range(ISL7998x_REG_P0_PRODUCT_ID_CODE,
> +                      ISL7998x_REG_P0_IRQ_SYNC_CTL),
> +     regmap_reg_range(ISL7998x_REG_P0_INTERRUPT_STATUS,
> +                      ISL7998x_REG_P0_CLOCK_DELAY),
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(0),
> +                      ISL7998x_REG_Px_DEC_PAGE(0)),
> +
> +     ISL7998x_REG_DECODER_ACA_READABLE_RANGE(1),
> +     ISL7998x_REG_DECODER_ACA_READABLE_RANGE(2),
> +     ISL7998x_REG_DECODER_ACA_READABLE_RANGE(3),
> +     ISL7998x_REG_DECODER_ACA_READABLE_RANGE(4),
> +
> +     regmap_reg_range(ISL7998x_REG_P5_LI_ENGINE_CTL,
> +                      ISL7998x_REG_P5_MIPI_SP_HS_TRL_CTL),
> +     regmap_reg_range(ISL7998x_REG_P5_FIFO_THRSH_CNT_1,
> +                      ISL7998x_REG_P5_PLL_ANA),
> +     regmap_reg_range(ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_1,
> +                      ISL7998x_REG_P5_HIST_LINE_CNT_2),
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(5),
> +                      ISL7998x_REG_Px_DEC_PAGE(5)),
> +};
> +
> +static const struct regmap_range isl7998x_writeable_ranges[] = {
> +     regmap_reg_range(ISL7998x_REG_P0_SW_RESET_CTL,
> +                      ISL7998x_REG_P0_IRQ_SYNC_CTL),
> +     regmap_reg_range(ISL7998x_REG_P0_CHAN_1_IRQ,
> +                      ISL7998x_REG_P0_SHORT_DIAG_IRQ_EN),
> +     regmap_reg_range(ISL7998x_REG_P0_CLOCK_DELAY,
> +                      ISL7998x_REG_P0_CLOCK_DELAY),
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(0),
> +                      ISL7998x_REG_Px_DEC_PAGE(0)),
> +
> +     ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(1),
> +     ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(2),
> +     ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(3),
> +     ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(4),
> +
> +     regmap_reg_range(ISL7998x_REG_P5_LI_ENGINE_CTL,
> +                      ISL7998x_REG_P5_ESC_MODE_TIME_CTL),
> +     regmap_reg_range(ISL7998x_REG_P5_MIPI_SP_HS_TRL_CTL,
> +                      ISL7998x_REG_P5_PLL_ANA),
> +     regmap_reg_range(ISL7998x_REG_P5_TOTAL_PF_LINE_CNT_1,
> +                      ISL7998x_REG_P5_HIST_LINE_CNT_2),
> +     regmap_reg_range(ISL7998x_REG_Px_DEC_PAGE(5),
> +                      ISL7998x_REG_Px_DEC_PAGE(5)),
> +
> +     ISL7998x_REG_DECODER_ACA_WRITEABLE_RANGE(0xf),
> +};
> +
> +static const struct regmap_range isl7998x_volatile_ranges[] = {
> +     regmap_reg_range(ISL7998x_REG_P0_MPP1_SYNC_CTL,
> +                      ISL7998x_REG_P0_IRQ_SYNC_CTL),
> +     regmap_reg_range(ISL7998x_REG_P0_INTERRUPT_STATUS,
> +                      ISL7998x_REG_P0_INTERRUPT_STATUS),
> +     regmap_reg_range(ISL7998x_REG_P0_CHAN_1_STATUS,
> +                      ISL7998x_REG_P0_SHORT_DIAG_STATUS),
> +
> +     ISL7998x_REG_DECODER_ACA_VOLATILE_RANGE(1),
> +     ISL7998x_REG_DECODER_ACA_VOLATILE_RANGE(2),
> +     ISL7998x_REG_DECODER_ACA_VOLATILE_RANGE(3),
> +     ISL7998x_REG_DECODER_ACA_VOLATILE_RANGE(4),
> +
> +     regmap_reg_range(ISL7998x_REG_P5_AUTO_TEST_ERR_DET,
> +                      ISL7998x_REG_P5_PIC_HEIGHT_LOW),
> +};
> +
> +static const struct regmap_access_table isl7998x_readable_table = {
> +     .yes_ranges = isl7998x_readable_ranges,
> +     .n_yes_ranges = ARRAY_SIZE(isl7998x_readable_ranges),
> +};
> +
> +static const struct regmap_access_table isl7998x_writeable_table = {
> +     .yes_ranges = isl7998x_writeable_ranges,
> +     .n_yes_ranges = ARRAY_SIZE(isl7998x_writeable_ranges),
> +};
> +
> +static const struct regmap_access_table isl7998x_volatile_table = {
> +     .yes_ranges = isl7998x_volatile_ranges,
> +     .n_yes_ranges = ARRAY_SIZE(isl7998x_volatile_ranges),
> +};
> +
> +static const struct regmap_range_cfg isl7998x_ranges[] = {
> +     {
> +             .range_min      = ISL7998x_REG_Pn_BASE(0),
> +             .range_max      = ISL7998x_REG_Px_ACA_XFER_HIST_HOST(0xf),
> +             .selector_reg   = ISL7998x_REG_Px_DEC_PAGE(0),
> +             .selector_mask  = ISL7998x_REG_Px_DEC_PAGE_MASK,
> +             .window_start   = 0,
> +             .window_len     = 256,
> +     }
> +};
> +
> +static const struct regmap_config isl7998x_regmap = {
> +     .reg_bits       = 8,
> +     .val_bits       = 8,
> +     .max_register   = ISL7998x_REG_Px_ACA_XFER_HIST_HOST(0xf),
> +     .ranges         = isl7998x_ranges,
> +     .num_ranges     = ARRAY_SIZE(isl7998x_ranges),
> +     .rd_table       = &isl7998x_readable_table,
> +     .wr_table       = &isl7998x_writeable_table,
> +     .volatile_table = &isl7998x_volatile_table,
> +     .cache_type     = REGCACHE_RBTREE,
> +};
> +
> +static int isl7998x_probe(struct i2c_client *client,
> +                      const struct i2c_device_id *did)
> +{
> +     struct device *dev = &client->dev;
> +     struct v4l2_fwnode_endpoint endpoint;

Please do initialise the bus_type field at least.

> +     struct device_node *ep;
> +     struct isl7998x *isl7998x;
> +     struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> +     u32 chip_id;
> +     int i, ret;
> +
> +     ret = i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA);
> +     if (!ret) {
> +             dev_warn(&adapter->dev,
> +                      "I2C-Adapter doesn't support I2C_FUNC_SMBUS_WORD\n");
> +             return -EIO;
> +     }
> +
> +     isl7998x = devm_kzalloc(dev, sizeof(*isl7998x), GFP_KERNEL);
> +     if (!isl7998x)
> +             return -ENOMEM;
> +
> +     /* Default to all four inputs active unless specified otherwise. */
> +     ret = of_property_read_u32(dev->of_node, "isil,num-inputs",
> +                                &isl7998x->nr_inputs);
> +     if (ret)
> +             isl7998x->nr_inputs = 4;
> +
> +     if (isl7998x->nr_inputs != 1 && isl7998x->nr_inputs != 2 &&
> +         isl7998x->nr_inputs != 4) {
> +             dev_err(dev, "Invalid number of inputs selected in DT\n");
> +             return -EINVAL;
> +     }
> +
> +     isl7998x->pd_gpio = devm_gpiod_get_optional(dev, "pd", GPIOD_OUT_HIGH);
> +     if (IS_ERR(isl7998x->pd_gpio)) {
> +             dev_err(dev, "Failed to retrieve/request PD GPIO: %ld\n",
> +                     PTR_ERR(isl7998x->pd_gpio));
> +             return PTR_ERR(isl7998x->pd_gpio);
> +     }
> +
> +     isl7998x->regmap = devm_regmap_init_i2c(client, &isl7998x_regmap);
> +     if (IS_ERR(isl7998x->regmap)) {
> +             ret = PTR_ERR(isl7998x->regmap);
> +             dev_err(dev, "Failed to allocate register map: %d\n", ret);
> +             return ret;
> +     }
> +
> +     ep = of_graph_get_next_endpoint(dev->of_node, NULL);
> +     if (!ep) {
> +             dev_err(dev, "Missing endpoint node\n");
> +             return -EINVAL;
> +     }
> +
> +     ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep), &endpoint);
> +     of_node_put(ep);
> +     if (ret) {
> +             dev_err(dev, "Failed to parse endpoint\n");
> +             return ret;
> +     }
> +
> +     if (endpoint.bus_type != V4L2_MBUS_CSI2_DPHY ||
> +         endpoint.bus.mipi_csi2.num_data_lanes == 0 ||
> +         endpoint.bus.mipi_csi2.num_data_lanes > 2) {
> +             dev_err(dev, "Invalid bus type or number of MIPI lanes\n");
> +             return -EINVAL;
> +     }
> +
> +     isl7998x->nr_mipi_lanes = endpoint.bus.mipi_csi2.num_data_lanes;
> +
> +     v4l2_i2c_subdev_init(&isl7998x->subdev, client, &isl7998x_subdev_ops);
> +     isl7998x->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +     isl7998x->pad.flags = MEDIA_PAD_FL_SOURCE;
> +     isl7998x->subdev.entity.ops = &isl7998x_entity_ops;
> +     isl7998x->subdev.entity.function = MEDIA_ENT_F_CAM_SENSOR;

This is definitely not a camera sensor.

MEDIA_ENT_F_VID_IF_BRIDGE perhaps?

How does the driver work without MC? E.g. how are the formats on the inputs
set up?

> +     ret = media_entity_pads_init(&isl7998x->subdev.entity, 1,
> +                                  &isl7998x->pad);
> +     if (ret < 0)
> +             return ret;
> +#endif
> +
> +     isl7998x->width = ISL7998x_WIDTH;
> +     isl7998x->height = ISL7998x_HEIGHT;
> +     isl7998x->fmt = &isl7998x_colour_fmts[0];
> +
> +     ret = v4l2_ctrl_handler_init(&isl7998x->ctrl_handler,
> +                                  2 + ARRAY_SIZE(isl7998x_ctrls));
> +     if (ret)
> +             return ret;
> +
> +     mutex_init(&isl7998x->ctrl_mutex);
> +     isl7998x->ctrl_handler.lock = &isl7998x->ctrl_mutex;
> +     isl7998x->link_freq = v4l2_ctrl_new_int_menu(&isl7998x->ctrl_handler,
> +                             &isl7998x_ctrl_ops, V4L2_CID_LINK_FREQ,
> +                             ARRAY_SIZE(link_freq_menu_items) - 1,
> +                             endpoint.bus.mipi_csi2.num_data_lanes == 2 ?
> +                             1 : 0, link_freq_menu_items);
> +     isl7998x->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;

Note that v4l2_ctrl_new_int_menu() returns NULL on error. Please also check
the control handler's error status when you're done setting up controls,
and call v4l2_ctrl_handler_free() in cleanup if there was an error.

> +
> +     for (i = 0; i < ARRAY_SIZE(isl7998x_ctrls); i++) {
> +             v4l2_ctrl_new_custom(&isl7998x->ctrl_handler,
> +                                  &isl7998x_ctrls[i], NULL);
> +     }

No need for braces.

> +
> +     v4l2_ctrl_new_std_menu_items(&isl7998x->ctrl_handler,
> +                             &isl7998x_ctrl_ops, V4L2_CID_TEST_PATTERN,
> +                             ARRAY_SIZE(isl7998x_test_pattern_menu) - 1,
> +                             0, 0, isl7998x_test_pattern_menu);
> +
> +     isl7998x->subdev.ctrl_handler = &isl7998x->ctrl_handler;
> +
> +     isl7998x->subdev.dev = dev;

The dev field is initialised to the same value by v4l2_i2c_subdev_init().
Please remove.

> +     ret = v4l2_async_register_subdev(&isl7998x->subdev);
> +     if (ret < 0)
> +             goto err_entity_cleanup;
> +
> +     /*
> +      * Turn the chip ON and keep it ON, otherwise the camera standard
> +      * detection takes about 600 mS every time we do VIDIOC_G_FMT.

"ms". Unless you meant Siemens, a unit of conductance.

> +      */
> +     if (isl7998x->pd_gpio)
> +             gpiod_set_value(isl7998x->pd_gpio, 0);
> +
> +     ret = regmap_read(isl7998x->regmap, ISL7998x_REG_P0_PRODUCT_ID_CODE,
> +                       &chip_id);
> +     if (ret) {
> +             dev_err(dev, "Failed to read ID register: %d\n", ret);
> +             goto err_init_cleanup;
> +     }
> +
> +     dev_info(dev, "ISL7998x found (id=%x)\n", chip_id);
> +
> +     ret = isl7998x_init(isl7998x);
> +     if (ret)
> +             goto err_init_cleanup;
> +
> +     ret = isl7998x_update_std(isl7998x);
> +     if (ret)
> +             goto err_init_cleanup;
> +
> +     return 0;
> +
> +err_init_cleanup:
> +     if (isl7998x->pd_gpio)
> +             gpiod_set_value(isl7998x->pd_gpio, 1);
> +err_entity_cleanup:
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +     media_entity_cleanup(&isl7998x->subdev.entity);
> +#endif

You can remove the #ifdef here.

Newlines are nice before labels and return (unless it's right after if).

> +     return ret;
> +}
> +
> +static int isl7998x_remove(struct i2c_client *client)
> +{
> +     struct isl7998x *isl7998x = i2c_to_isl7998x(client);
> +
> +     if (isl7998x->pd_gpio)
> +             gpiod_set_value(isl7998x->pd_gpio, 1);
> +     v4l2_async_unregister_subdev(&isl7998x->subdev);
> +     v4l2_ctrl_handler_free(isl7998x->subdev.ctrl_handler);
> +     media_entity_cleanup(&isl7998x->subdev.entity);
> +
> +     return 0;
> +}
> +
> +static const struct of_device_id isl7998x_of_match[] = {
> +     { .compatible = "isil,isl79987", },
> +     {},
> +};
> +MODULE_DEVICE_TABLE(of, isl7998x_of_match);
> +
> +static const struct i2c_device_id isl7998x_id[] = {
> +     { "isl79987", 0 },
> +     { }
> +};
> +MODULE_DEVICE_TABLE(i2c, isl7998x_id);
> +
> +static struct i2c_driver isl7998x_i2c_driver = {
> +     .driver = {
> +             .name = "isl7998x",
> +             .of_match_table = of_match_ptr(isl7998x_of_match),
> +     },
> +     .probe          = isl7998x_probe,
> +     .remove         = isl7998x_remove,
> +     .id_table       = isl7998x_id,

Use probe_new, and you can omit the id_table.

> +};
> +
> +module_i2c_driver(isl7998x_i2c_driver);
> +
> +MODULE_DESCRIPTION("Intersil ISL7998x BT656-to-MIPI-CSI2 driver");
> +MODULE_AUTHOR("Marek Vasut <ma...@denx.de>");
> +MODULE_LICENSE("GPL");

The SPDX header indicates GPL v2.0. Which one is correct?

-- 
Kind regards,

Sakari Ailus
sakari.ai...@linux.intel.com

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