From 95e681ca3b65e4ce3d2537b47672d787b7d30375 Mon Sep 17 00:00:00 2001
From: Abhinav Kumar <quic_abhinavk@quicinc.com>
Date: Thu, 7 Sep 2023 18:26:16 -0700
Subject: [PATCH] drm/msm/dpu: change _dpu_plane_calc_bw() to use u64 to avoid overflow
Git-commit: 95e681ca3b65e4ce3d2537b47672d787b7d30375
Patch-mainline: v6.6-rc6
References: git-fixes
_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@linaro.org>
Reported-by: Nia Espera <nespera@igalia.com>
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/32
Tested-by: Nia Espera <nespera@igalia.com>
Patchwork: https://patchwork.freedesktop.org/patch/556288/
Link: https://lore.kernel.org/r/20230908012616.20654-1-quic_abhinavk@quicinc.com
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
@@ -158,6 +158,7 @@ static void _dpu_plane_calc_bw(struct dr
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;
@@ -180,13 +181,12 @@ static void _dpu_plane_calc_bw(struct dr
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_prefill_bw =
- src_width * hw_latency_lines * fps * fmt->bpp *
- scale_factor * mode->vtotal;
+ plane_pixel_rate = src_width * mode->vtotal * fps;
+ plane_bit_rate = plane_pixel_rate * fmt->bpp;
+
+ plane_bw = plane_bit_rate * scale_factor;
+
+ plane_prefill_bw = plane_bw * hw_latency_lines;
if ((vbp+vpw) > hw_latency_lines)
do_div(plane_prefill_bw, (vbp+vpw));