[PATCH v3 4/4] drm/msm/dpu: fix video mode DSC INTF timing width calculation

[Alexander Koskovich <akoskovich@pm.me>]

Using bits_per_component * 3 as the divisor for the compressed INTF
timing width produces constant FIFO errors for the BOE BF068MWM-TD0
panel due to bits_per_component being 10 which results in a divisor
of 30 instead of 24.

Regardless of the compression ratio and pixel depth, 24 bits of
compressed data are transferred per pclk, so the divisor should
always be 24.

Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index 0ba777bda253..5419ef0be137 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -122,19 +122,18 @@ static void drm_mode_to_intf_timing_params(
 	}
 
 	/*
-	 * for DSI, if compression is enabled, then divide the horizonal active
-	 * timing parameters by compression ratio. bits of 3 components(R/G/B)
-	 * is compressed into bits of 1 pixel.
+	 * For DSI, if DSC is enabled, 24 bits of compressed data are
+	 * transferred per pclk regardless of the source pixel depth.
 	 */
 	if (phys_enc->hw_intf->cap->type != INTF_DP && timing->compression_en) {
 		struct drm_dsc_config *dsc =
 		       dpu_encoder_get_dsc_config(phys_enc->parent);
+
 		/*
 		 * TODO: replace drm_dsc_get_bpp_int with logic to handle
 		 * fractional part if there is fraction
 		 */
-		timing->width = timing->width * drm_dsc_get_bpp_int(dsc) /
-				(dsc->bits_per_component * 3);
+		timing->width = timing->width * drm_dsc_get_bpp_int(dsc) / 24;
 		timing->xres = timing->width;
 	}
 }

-- 
2.53.0