This is a note to let you know that I've just added the patch titled
drm/msm/dpu: change _dpu_plane_calc_bw() to use u64 to avoid overflow
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-msm-dpu-change-_dpu_plane_calc_bw-to-use-u64-to-.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 97ec638293b453dc11317abca14c0d8b6054b563
Author: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
Date: Thu Sep 7 18:26:16 2023 -0700
drm/msm/dpu: change _dpu_plane_calc_bw() to use u64 to avoid overflow
[ Upstream commit 95e681ca3b65e4ce3d2537b47672d787b7d30375 ]
_dpu_plane_calc_bw() uses integer variables to calculate the bandwidth
used during plane bandwidth calculations. However for high resolution
displays this overflows easily and leads to below errors
[dpu error]crtc83 failed performance check -7
Promote the intermediate variables to u64 to avoid overflow.
changes in v2:
- change to u64 where actually needed in the math
Fixes: c33b7c0389e1 ("drm/msm/dpu: add support for clk and bw scaling for display")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Reported-by: Nia Espera <nespera@xxxxxxxxxx>
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/32
Tested-by: Nia Espera <nespera@xxxxxxxxxx>
Patchwork: https://patchwork.freedesktop.org/patch/556288/
Link: https://lore.kernel.org/r/20230908012616.20654-1-quic_abhinavk@xxxxxxxxxxx
Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
index 7ea90d25a3b69..8aa9f2335f57a 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
@@ -147,6 +147,7 @@ static void _dpu_plane_calc_bw(struct drm_plane *plane,
const struct dpu_format *fmt = NULL;
struct dpu_kms *dpu_kms = _dpu_plane_get_kms(plane);
int src_width, src_height, dst_height, fps;
+ u64 plane_pixel_rate, plane_bit_rate;
u64 plane_prefill_bw;
u64 plane_bw;
u32 hw_latency_lines;
@@ -168,13 +169,12 @@ static void _dpu_plane_calc_bw(struct drm_plane *plane,
scale_factor = src_height > dst_height ?
mult_frac(src_height, 1, dst_height) : 1;
- plane_bw =
- src_width * mode->vtotal * fps * fmt->bpp *
- scale_factor;
+ plane_pixel_rate = src_width * mode->vtotal * fps;
+ plane_bit_rate = plane_pixel_rate * fmt->bpp;
- plane_prefill_bw =
- src_width * hw_latency_lines * fps * fmt->bpp *
- scale_factor * mode->vtotal;
+ plane_bw = plane_bit_rate * scale_factor;
+
+ plane_prefill_bw = plane_bw * hw_latency_lines;
do_div(plane_prefill_bw, (vbp+vpw));
