Change the method of frame rate calc which can get more accurate
frame rate.

data rate = pixel_clock * bit_per_pixel / lanes
Adjust hfp_wc to adapt the additional phy_data

if MIPI_DSI_MODE_VIDEO_BURST
        hfp_wc = hfp * bpp - data_phy_cycles * lanes - 12 - 6;
else
        hfp_wc = hfp * bpp - data_phy_cycles * lanes - 12;

Note:
//(2: 1 for sync, 1 for phy idle)
data_phy_cycles = T_hs_exit + T_lpx + T_hs_prepare + T_hs_zero + 2;

bpp: bit per pixel

Signed-off-by: Jitao Shi <jitao....@mediatek.com>
Tested-by: Ryan Case <ryandc...@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 122 ++++++++++++++++++++---------
 1 file changed, 83 insertions(+), 39 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c 
b/drivers/gpu/drm/mediatek/mtk_dsi.c
index abf6ddec5db6..558727c60ba3 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -144,12 +144,6 @@
 #define DATA_0                         (0xff << 16)
 #define DATA_1                         (0xff << 24)
 
-#define T_LPX          5
-#define T_HS_PREP      6
-#define T_HS_TRAIL     8
-#define T_HS_EXIT      7
-#define T_HS_ZERO      10
-
 #define NS_TO_CYCLE(n, c)    ((n) / (c) + (((n) % (c)) ? 1 : 0))
 
 #define MTK_DSI_HOST_IS_READ(type) \
@@ -158,6 +152,25 @@
        (type == MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM) || \
        (type == MIPI_DSI_DCS_READ))
 
+struct mtk_phy_timing {
+       u32 lpx;
+       u32 da_hs_prepare;
+       u32 da_hs_zero;
+       u32 da_hs_trail;
+
+       u32 ta_go;
+       u32 ta_sure;
+       u32 ta_get;
+       u32 da_hs_exit;
+
+       u32 clk_hs_zero;
+       u32 clk_hs_trail;
+
+       u32 clk_hs_prepare;
+       u32 clk_hs_post;
+       u32 clk_hs_exit;
+};
+
 struct phy;
 
 struct mtk_dsi_driver_data {
@@ -182,12 +195,13 @@ struct mtk_dsi {
        struct clk *digital_clk;
        struct clk *hs_clk;
 
-       u32 data_rate;
+       u64 data_rate;
 
        unsigned long mode_flags;
        enum mipi_dsi_pixel_format format;
        unsigned int lanes;
        struct videomode vm;
+       struct mtk_phy_timing phy_timing;
        int refcount;
        bool enabled;
        u32 irq_data;
@@ -221,17 +235,36 @@ static void mtk_dsi_phy_timconfig(struct mtk_dsi *dsi)
 {
        u32 timcon0, timcon1, timcon2, timcon3;
        u32 ui, cycle_time;
+       struct mtk_phy_timing *timing = &dsi->phy_timing;
+
+       ui = 1000000000 / dsi->data_rate;
+       cycle_time = 8000000000 / dsi->data_rate;
+
+       timing->lpx = NS_TO_CYCLE(60, cycle_time);
+       timing->da_hs_prepare = NS_TO_CYCLE(40 + 5 * ui, cycle_time);
+       timing->da_hs_zero = NS_TO_CYCLE(110 + 6 * ui, cycle_time);
+       timing->da_hs_trail = NS_TO_CYCLE(80 + 4 * ui, cycle_time);
 
-       ui = 1000 / dsi->data_rate + 0x01;
-       cycle_time = 8000 / dsi->data_rate + 0x01;
+       timing->ta_go = 4 * timing->lpx;
+       timing->ta_sure = 3 * timing->lpx / 2;
+       timing->ta_get = 5 * timing->lpx;
+       timing->da_hs_exit = 2 * timing->lpx;
 
-       timcon0 = T_LPX | T_HS_PREP << 8 | T_HS_ZERO << 16 | T_HS_TRAIL << 24;
-       timcon1 = 4 * T_LPX | (3 * T_LPX / 2) << 8 | 5 * T_LPX << 16 |
-                 T_HS_EXIT << 24;
-       timcon2 = ((NS_TO_CYCLE(0x64, cycle_time) + 0xa) << 24) |
-                 (NS_TO_CYCLE(0x150, cycle_time) << 16);
-       timcon3 = NS_TO_CYCLE(0x40, cycle_time) | (2 * T_LPX) << 16 |
-                 NS_TO_CYCLE(80 + 52 * ui, cycle_time) << 8;
+       timing->clk_hs_zero = NS_TO_CYCLE(336, cycle_time);
+       timing->clk_hs_trail = NS_TO_CYCLE(100, cycle_time) + 10;
+
+       timing->clk_hs_prepare = NS_TO_CYCLE(64, cycle_time);
+       timing->clk_hs_post = NS_TO_CYCLE(80 + 52 * ui, cycle_time);
+       timing->clk_hs_exit = 2 * timing->lpx;
+
+       timcon0 = timing->lpx | timing->da_hs_prepare << 8 |
+                 timing->da_hs_zero << 16 | timing->da_hs_trail << 24;
+       timcon1 = timing->ta_go | timing->ta_sure << 8 |
+                 timing->ta_get << 16 | timing->da_hs_exit << 24;
+       timcon2 = 1 << 8 | timing->clk_hs_zero << 16 |
+                 timing->clk_hs_trail << 24;
+       timcon3 = timing->clk_hs_prepare | timing->clk_hs_post << 8 |
+                 timing->clk_hs_exit << 16;
 
        writel(timcon0, dsi->regs + DSI_PHY_TIMECON0);
        writel(timcon1, dsi->regs + DSI_PHY_TIMECON1);
@@ -418,7 +451,8 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
        u32 horizontal_sync_active_byte;
        u32 horizontal_backporch_byte;
        u32 horizontal_frontporch_byte;
-       u32 dsi_tmp_buf_bpp;
+       u32 dsi_tmp_buf_bpp, data_phy_cycles;
+       struct mtk_phy_timing *timing = &dsi->phy_timing;
 
        struct videomode *vm = &dsi->vm;
 
@@ -433,7 +467,8 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
        writel(vm->vactive, dsi->regs + DSI_VACT_NL);
 
        if (dsi->driver_data->has_size_ctl)
-               writel(vm->vactive << 16 | vm->hactive, dsi->regs + 
DSI_SIZE_CON);
+               writel(vm->vactive << 16 | vm->hactive,
+                      dsi->regs + DSI_SIZE_CON);
 
        horizontal_sync_active_byte = (vm->hsync_len * dsi_tmp_buf_bpp - 10);
 
@@ -444,7 +479,34 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
                horizontal_backporch_byte = ((vm->hback_porch + vm->hsync_len) *
                        dsi_tmp_buf_bpp - 10);
 
-       horizontal_frontporch_byte = (vm->hfront_porch * dsi_tmp_buf_bpp - 12);
+       data_phy_cycles = timing->lpx + timing->da_hs_prepare +
+                                 timing->da_hs_zero + timing->da_hs_exit + 2;
+
+       if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
+               if (vm->hfront_porch * dsi_tmp_buf_bpp >
+                   data_phy_cycles * dsi->lanes + 18) {
+                       horizontal_frontporch_byte = vm->hfront_porch *
+                                                    dsi_tmp_buf_bpp -
+                                                    data_phy_cycles *
+                                                    dsi->lanes - 18;
+               } else {
+                       DRM_WARN("HFP less than d-phy, FPS will under 60Hz\n");
+                       horizontal_frontporch_byte = vm->hfront_porch *
+                                                    dsi_tmp_buf_bpp;
+               }
+       } else {
+               if (vm->hfront_porch * dsi_tmp_buf_bpp >
+                   data_phy_cycles * dsi->lanes + 12) {
+                       horizontal_frontporch_byte = vm->hfront_porch *
+                                                    dsi_tmp_buf_bpp -
+                                                    data_phy_cycles *
+                                                    dsi->lanes - 12;
+               } else {
+                       DRM_WARN("HFP less than d-phy, FPS will under 60Hz\n");
+                       horizontal_frontporch_byte = vm->hfront_porch *
+                                                    dsi_tmp_buf_bpp;
+               }
+       }
 
        writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC);
        writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC);
@@ -544,8 +606,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
 {
        struct device *dev = dsi->dev;
        int ret;
-       u64 pixel_clock, total_bits;
-       u32 htotal, htotal_bits, bit_per_pixel, overhead_cycles, overhead_bits;
+       u32 bit_per_pixel;
 
        if (++dsi->refcount != 1)
                return 0;
@@ -564,24 +625,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
                break;
        }
 
-       /**
-        * htotal_time = htotal * byte_per_pixel / num_lanes
-        * overhead_time = lpx + hs_prepare + hs_zero + hs_trail + hs_exit
-        * mipi_ratio = (htotal_time + overhead_time) / htotal_time
-        * data_rate = pixel_clock * bit_per_pixel * mipi_ratio / num_lanes;
-        */
-       pixel_clock = dsi->vm.pixelclock;
-       htotal = dsi->vm.hactive + dsi->vm.hback_porch + dsi->vm.hfront_porch +
-                       dsi->vm.hsync_len;
-       htotal_bits = htotal * bit_per_pixel;
-
-       overhead_cycles = T_LPX + T_HS_PREP + T_HS_ZERO + T_HS_TRAIL +
-                       T_HS_EXIT;
-       overhead_bits = overhead_cycles * dsi->lanes * 8;
-       total_bits = htotal_bits + overhead_bits;
-
-       dsi->data_rate = DIV_ROUND_UP_ULL(pixel_clock * total_bits,
-                                         htotal * dsi->lanes);
+       dsi->data_rate = dsi->vm.pixelclock * bit_per_pixel / dsi->lanes;
 
        ret = clk_set_rate(dsi->hs_clk, dsi->data_rate);
        if (ret < 0) {
-- 
2.21.0

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