Quoting David Heidelberg (2026-02-28 22:37:57)
> On 18/01/2026 13:05, Kieran Bingham wrote:
> > Quoting Bryan O'Donoghue (2026-01-17 21:38:17)
> >> On 17/01/2026 15:36, David Heidelberg via B4 Relay wrote:
> >>> From: David Heidelberg <[email protected]>
> >>>
> >>> So far, only D-PHY mode was supported, which uses even bits when enabling
> >>> or masking lanes. For C-PHY configuration, the hardware instead requires
> >>> using the odd bits.
> >>>
> >>> Since there can be unrecognized configuration allow returning failure.
> >>>
> >>> Signed-off-by: David Heidelberg <[email protected]>
> >>> ---
> >>> .../platform/qcom/camss/camss-csiphy-2ph-1-0.c | 8 ++--
> >>> .../platform/qcom/camss/camss-csiphy-3ph-1-0.c | 49
> >>> +++++++++++++++++-----
> >>> drivers/media/platform/qcom/camss/camss-csiphy.c | 4 +-
> >>> drivers/media/platform/qcom/camss/camss-csiphy.h | 6 +--
> >>> 4 files changed, 47 insertions(+), 20 deletions(-)
> >>>
> >>> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
> >>> b/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
> >>> index 9d67e7fa6366a..bb4b91f69616b 100644
> >>> --- a/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
> >>> +++ b/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
> >>> @@ -94,9 +94,9 @@ static u8 csiphy_settle_cnt_calc(s64 link_freq, u32
> >>> timer_clk_rate)
> >>> return settle_cnt;
> >>> }
> >>>
> >>> -static void csiphy_lanes_enable(struct csiphy_device *csiphy,
> >>> - struct csiphy_config *cfg,
> >>> - s64 link_freq, u8 lane_mask)
> >>> +static int csiphy_lanes_enable(struct csiphy_device *csiphy,
> >>> + struct csiphy_config *cfg,
> >>> + s64 link_freq, u8 lane_mask)
> >>> {
> >>> struct csiphy_lanes_cfg *c = &cfg->csi2->lane_cfg;
> >>> u8 settle_cnt;
> >>> @@ -132,6 +132,8 @@ static void csiphy_lanes_enable(struct csiphy_device
> >>> *csiphy,
> >>> writel_relaxed(0x3f, csiphy->base +
> >>> CAMSS_CSI_PHY_INTERRUPT_CLEARn(l));
> >>> }
> >>> +
> >>> + return 0;
> >>> }
> >>>
> >>> static void csiphy_lanes_disable(struct csiphy_device *csiphy,
> >>> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy-3ph-1-0.c
> >>> b/drivers/media/platform/qcom/camss/camss-csiphy-3ph-1-0.c
> >>> index 4154832745525..f3a8625511e1e 100644
> >>> --- a/drivers/media/platform/qcom/camss/camss-csiphy-3ph-1-0.c
> >>> +++ b/drivers/media/platform/qcom/camss/camss-csiphy-3ph-1-0.c
> >>> @@ -14,6 +14,7 @@
> >>> #include <linux/delay.h>
> >>> #include <linux/interrupt.h>
> >>> #include <linux/io.h>
> >>> +#include <linux/media-bus-format.h>
> >>>
> >>> #define CSIPHY_3PH_LNn_CFG1(n) (0x000 + 0x100 *
> >>> (n))
> >>> #define CSIPHY_3PH_LNn_CFG1_SWI_REC_DLY_PRG (BIT(7) | BIT(6))
> >>> @@ -993,13 +994,22 @@ static void csiphy_gen2_config_lanes(struct
> >>> csiphy_device *csiphy,
> >>>
> >>> static u8 csiphy_get_lane_mask(struct csiphy_lanes_cfg *lane_cfg)
> >>> {
> >>> - u8 lane_mask;
> >>> - int i;
> >>> + u8 lane_mask = 0;
> >>>
> >>> - lane_mask = CSIPHY_3PH_CMN_CSI_COMMON_CTRL5_CLK_ENABLE;
> >>> + switch (lane_cfg->phy_cfg) {
> >>> + case V4L2_MBUS_CSI2_CPHY:
> >>> + for (int i = 0; i < lane_cfg->num_data; i++)
> >>> + lane_mask |= (1 << lane_cfg->data[i].pos) + 1;
> >>
> >> 1 << anything == BIT(anything)
> >>
> >> I've always disliked the look of this code and now it occurs to me why.
> >>
> >> This code is analogous to:
> >>
> >> lane_mask |= BIT(lane_cfg->data[i].pos) + 1);
> >
> > I see that addition to a bit mask and get a little bit scared.
> >
> > This gives:
> > pos mask
> > 0 0b00000010 (note 0 bit is zero here but 1 on all others)
> > 1 0b00000011
> > 2 0b00000101
> > 3 0b00001001
> > 4 0b00010001
> >
> > Is that expected?
> >
> > Can data[i].pos ever be position 0 ??
> >
> > I assume this starts at position 1 - and the +1 here is to always set
> > the zeroth bit ?
> >
> > Perhapse this might be precise to convey that in such a case?
> >
> > lane_mask |= BIT(pos) | 1;
> >
> > I guess it depends on what this is really being used for which I don't
> > have in my context.
>
> Ok, I started looking again into the lovely downstream code.
>
> D-PHY has bits 0b0D_D_D_D
> C-PHY has bits 0b0_C_C_C_
>
> so for some reason it worked in my usecase without proper lane mask, but
> the original formula should be
>
> - lane_mask |= (1 << lane_cfg->data[i].pos) + 1;
> + lane_mask |= (1 << lane_cfg->data[i].pos + 1);
>
> Thus
>
> BIT(lane_cfg->data[i].pos + 1);
That looks a lot more sane!
--
Kieran
>
> >
> > --
> > Kieran
> >
> >
> >
> >>
> >> but BIT() is less janky and more upstreamy.
> >>
> >> janky/upstreamy - this is the on-point technical argument y'all came
> >> here for :)
> >>
> >>> + break;
> >>> + case V4L2_MBUS_CSI2_DPHY:
> >>> + lane_mask = CSIPHY_3PH_CMN_CSI_COMMON_CTRL5_CLK_ENABLE;
> >>>
> >>> - for (i = 0; i < lane_cfg->num_data; i++)
> >>> - lane_mask |= 1 << lane_cfg->data[i].pos;
> >>> + for (int i = 0; i < lane_cfg->num_data; i++)
> >>> + lane_mask |= 1 << lane_cfg->data[i].pos;
> >>> + break;
> >>> + default:
> >>> + break;
> >>> + }
> >>>
> >>> return lane_mask;
> >>> }
> >>> @@ -1027,10 +1037,11 @@ static bool csiphy_is_gen2(u32 version)
> >>> return ret;
> >>> }
> >>>
> >>> -static void csiphy_lanes_enable(struct csiphy_device *csiphy,
> >>> - struct csiphy_config *cfg,
> >>> - s64 link_freq, u8 lane_mask)
> >>> +static int csiphy_lanes_enable(struct csiphy_device *csiphy,
> >>> + struct csiphy_config *cfg,
> >>> + s64 link_freq, u8 lane_mask)
> >>> {
> >>> + struct device *dev = csiphy->camss->dev;
> >>> struct csiphy_lanes_cfg *c = &cfg->csi2->lane_cfg;
> >>> struct csiphy_device_regs *regs = csiphy->regs;
> >>> u8 settle_cnt;
> >>> @@ -1039,9 +1050,23 @@ static void csiphy_lanes_enable(struct
> >>> csiphy_device *csiphy,
> >>>
> >>> settle_cnt = csiphy_settle_cnt_calc(link_freq,
> >>> csiphy->timer_clk_rate);
> >>>
> >>> - val = CSIPHY_3PH_CMN_CSI_COMMON_CTRL5_CLK_ENABLE;
> >>> - for (i = 0; i < c->num_data; i++)
> >>> - val |= BIT(c->data[i].pos * 2);
> >>> + val = 0;
> >>> +
> >>> + switch (c->phy_cfg) {
> >>> + case V4L2_MBUS_CSI2_CPHY:
> >>> + for (i = 0; i < c->num_data; i++)
> >>> + val |= BIT((c->data[i].pos * 2) + 1);
> >>> + break;
> >>> + case V4L2_MBUS_CSI2_DPHY:
> >>> + val = CSIPHY_3PH_CMN_CSI_COMMON_CTRL5_CLK_ENABLE;
> >>> +
> >>> + for (i = 0; i < c->num_data; i++)
> >>> + val |= BIT(c->data[i].pos * 2);
> >>> + break;
> >>> + default:
> >>> + dev_err(dev, "Unsupported bus type %d\n", c->phy_cfg);
> >>> + return -EINVAL;
> >>> + }
> >>>
> >>> writel_relaxed(val, csiphy->base +
> >>> CSIPHY_3PH_CMN_CSI_COMMON_CTRLn(regs->offset, 5));
> >>> @@ -1068,6 +1093,8 @@ static void csiphy_lanes_enable(struct
> >>> csiphy_device *csiphy,
> >>> writel_relaxed(0, csiphy->base +
> >>>
> >>> CSIPHY_3PH_CMN_CSI_COMMON_CTRLn(regs->offset, i));
> >>> }
> >>> +
> >>> + return 0;
> >>> }
> >>>
> >>> static void csiphy_lanes_disable(struct csiphy_device *csiphy,
> >>> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.c
> >>> b/drivers/media/platform/qcom/camss/camss-csiphy.c
> >>> index 62623393f4144..08dd238e52799 100644
> >>> --- a/drivers/media/platform/qcom/camss/camss-csiphy.c
> >>> +++ b/drivers/media/platform/qcom/camss/camss-csiphy.c
> >>> @@ -295,9 +295,7 @@ static int csiphy_stream_on(struct csiphy_device
> >>> *csiphy)
> >>> wmb();
> >>> }
> >>>
> >>> - csiphy->res->hw_ops->lanes_enable(csiphy, cfg, link_freq,
> >>> lane_mask);
> >>> -
> >>> - return 0;
> >>> + return csiphy->res->hw_ops->lanes_enable(csiphy, cfg, link_freq,
> >>> lane_mask);
> >>
> >> ick.
> >>
> >> More high brow stuff from bod here but, more seriously this is three
> >> levels of indirection deep and the statement keeps getting longer.
> >>
> >> Could you get a pointer to hw_ops() to reduce this down a bit.
> >>
> >>> }
> >>>
> >>> /*
> >>> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.h
> >>> b/drivers/media/platform/qcom/camss/camss-csiphy.h
> >>> index d198171700e73..21cf2ce931c1d 100644
> >>> --- a/drivers/media/platform/qcom/camss/camss-csiphy.h
> >>> +++ b/drivers/media/platform/qcom/camss/camss-csiphy.h
> >>> @@ -73,9 +73,9 @@ struct csiphy_hw_ops {
> >>> void (*hw_version_read)(struct csiphy_device *csiphy,
> >>> struct device *dev);
> >>> void (*reset)(struct csiphy_device *csiphy);
> >>> - void (*lanes_enable)(struct csiphy_device *csiphy,
> >>> - struct csiphy_config *cfg,
> >>> - s64 link_freq, u8 lane_mask);
> >>> + int (*lanes_enable)(struct csiphy_device *csiphy,
> >>> + struct csiphy_config *cfg,
> >>> + s64 link_freq, u8 lane_mask);
> >>> void (*lanes_disable)(struct csiphy_device *csiphy,
> >>> struct csiphy_config *cfg);
> >>> irqreturn_t (*isr)(int irq, void *dev);
> >>>
> >>
> >> With those tweaks.
> >>
> >> Reviewed-by: Bryan O'Donoghue <[email protected]>
> >>
> >> ---
> >> bod
>
> --
> David Heidelberg
>
