6.12-stable review patch. If anyone has any objections, please let me know.
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From: Marijn Suijten marijn.suijten@somainline.org
[ Upstream commit 144429831f447223253a0e4376489f84ff37d1a7 ]
What used to be the input_10_bits boolean - feeding into the lowest bit of DSC_ENC - on MSM downstream turned into an accidental OR with the full bits_per_component number when it was ported to the upstream kernel.
On typical bpc=8 setups we don't notice this because line_buf_depth is always an odd value (it contains bpc+1) and will also set the 4th bit after left-shifting by 3 (hence this |= bits_per_component is a no-op).
Now that guards are being removed to allow more bits_per_component values besides 8 (possible since commit 49fd30a7153b ("drm/msm/dsi: use DRM DSC helpers for DSC setup")), a bpc of 10 will instead clash with the 5th bit which is convert_rgb. This is "fortunately" also always set to true by MSM's dsi_populate_dsc_params() already, but once a bpc of 12 starts being used it'll write into simple_422 which is normally false.
To solve all these overlaps, simply replicate downstream code and only set this lowest bit if bits_per_component is equal to 10. It is unclear why DSC requires this only for bpc=10 but not bpc=12, and also notice that this lowest bit wasn't set previously despite having a panel and patch on the list using it without any mentioned issues.
Fixes: c110cfd1753e ("drm/msm/disp/dpu1: Add support for DSC") Signed-off-by: Marijn Suijten marijn.suijten@somainline.org Reviewed-by: Abhinav Kumar quic_abhinavk@quicinc.com Reviewed-by: Konrad Dybcio konrad.dybcio@oss.qualcomm.com Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Patchwork: https://patchwork.freedesktop.org/patch/636311/ Link: https://lore.kernel.org/r/20250211-dsc-10-bit-v1-1-1c85a9430d9a@somainline.o... Signed-off-by: Abhinav Kumar quic_abhinavk@quicinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c index 5e9aad1b2aa28..d1e0fb2139765 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c @@ -52,6 +52,7 @@ static void dpu_hw_dsc_config(struct dpu_hw_dsc *hw_dsc, u32 slice_last_group_size; u32 det_thresh_flatness; bool is_cmd_mode = !(mode & DSC_MODE_VIDEO); + bool input_10_bits = dsc->bits_per_component == 10;
DPU_REG_WRITE(c, DSC_COMMON_MODE, mode);
@@ -68,7 +69,7 @@ static void dpu_hw_dsc_config(struct dpu_hw_dsc *hw_dsc, data |= (dsc->line_buf_depth << 3); data |= (dsc->simple_422 << 2); data |= (dsc->convert_rgb << 1); - data |= dsc->bits_per_component; + data |= input_10_bits;
DPU_REG_WRITE(c, DSC_ENC, data);