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| author | Marijn Suijten <marijn.suijten@somainline.org> | 2022-10-26 21:28:24 +0300 |
|---|---|---|
| committer | Dmitry Baryshkov <dmitry.baryshkov@linaro.org> | 2022-11-04 17:39:41 +0300 |
| commit | cc84b66be223d36a3d10d59d68ba647e72db3099 (patch) | |
| tree | bdcbc1b6407614c62884dc76d1c476ab400dc810 /drivers/gpu/drm/msm/dsi | |
| parent | 0b55f6bc46be7a6f90ebae4666b7463b666958ee (diff) | |
| download | linux-cc84b66be223d36a3d10d59d68ba647e72db3099.tar.xz | |
drm/msm/dsi: Prevent signed BPG offsets from bleeding into adjacent bits
The bpg_offset array contains negative BPG offsets which fill the full 8
bits of a char thanks to two's complement: this however results in those
bits bleeding into the next field when the value is packed into DSC PPS
by the drm_dsc_helper function, which only expects range_bpg_offset to
contain 6-bit wide values. As a consequence random slices appear
corrupted on-screen (tested on a Sony Tama Akatsuki device with sdm845).
Use AND operators to limit these two's complement values to 6 bits,
similar to the AMD and i915 drivers.
Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data")
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/508941/
Link: https://lore.kernel.org/r/20221026182824.876933-11-marijn.suijten@somainline.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Diffstat (limited to 'drivers/gpu/drm/msm/dsi')
| -rw-r--r-- | drivers/gpu/drm/msm/dsi/dsi_host.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index c229cf6eeb9c..89aadd3b3202 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1782,7 +1782,11 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc for (i = 0; i < DSC_NUM_BUF_RANGES; i++) { dsc->rc_range_params[i].range_min_qp = min_qp[i]; dsc->rc_range_params[i].range_max_qp = max_qp[i]; - dsc->rc_range_params[i].range_bpg_offset = bpg_offset[i]; + /* + * Range BPG Offset contains two's-complement signed values that fill + * 8 bits, yet the registers and DCS PPS field are only 6 bits wide. + */ + dsc->rc_range_params[i].range_bpg_offset = bpg_offset[i] & DSC_RANGE_BPG_OFFSET_MASK; } dsc->initial_offset = 6144; /* Not bpp 12 */ |