diff options
| author | Chris Park <Chris.Park@amd.com> | 2020-11-24 20:11:25 -0500 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2020-12-09 10:06:39 -0500 |
| commit | c2ffe78b8b1354603a7d5afb719b2a6dfbb582da (patch) | |
| tree | 08b953461a1ab0f2aac9946c2664ae59559edfbf /drivers/gpu | |
| parent | 2343e9d2c5a94459b9de92649f1650e36eb79a10 (diff) | |
drm/amd/display: Prevent bandwidth overflow
[Why]
At very high pixel clock, bandwidth calculation exceeds 32 bit size
and overflow value. This causes the resulting selection of link rate
to be inaccurate.
[How]
Change order of operation and use fixed point to deal with integer
accuracy. Also address bug found when forcing link rate.
Signed-off-by: Chris Park <Chris.Park@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/amd/display/dc/core/dc_link.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c index fec87a2e210c..5b0cedfa824a 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -3394,10 +3394,13 @@ uint32_t dc_bandwidth_in_kbps_from_timing( { uint32_t bits_per_channel = 0; uint32_t kbps; + struct fixed31_32 link_bw_kbps; if (timing->flags.DSC) { - kbps = (timing->pix_clk_100hz * timing->dsc_cfg.bits_per_pixel); - kbps = kbps / 160 + ((kbps % 160) ? 1 : 0); + link_bw_kbps = dc_fixpt_from_int(timing->pix_clk_100hz); + link_bw_kbps = dc_fixpt_div_int(link_bw_kbps, 160); + link_bw_kbps = dc_fixpt_mul_int(link_bw_kbps, timing->dsc_cfg.bits_per_pixel); + kbps = dc_fixpt_ceil(link_bw_kbps); return kbps; } |