This is a note to let you know that I've just added the patch titled
drm/amd/display: Fix possible underflow for displays with large vblank
to the 6.4-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-amd-display-fix-possible-underflow-for-displays-.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 04a62bd458bc032a71edbb5273ebbd4d406be41f
Author: Daniel Miess <daniel.miess@xxxxxxx>
Date: Tue Apr 25 14:29:48 2023 -0400
drm/amd/display: Fix possible underflow for displays with large vblank
[ Upstream commit 1a4bcdbea4319efeb26cc4b05be859a7867e02dc ]
[Why]
Underflow observed when using a display with a large vblank region
and low refresh rate
[How]
Simplify calculation of vblank_nom
Increase value for VBlankNomDefaultUS to 800us
Reviewed-by: Jun Lei <jun.lei@xxxxxxx>
Acked-by: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
Signed-off-by: Daniel Miess <daniel.miess@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Stable-dep-of: 2a9482e55968 ("drm/amd/display: Prevent vtotal from being set to 0")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
index 1d00eb9e73c62..554152371eb53 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
@@ -33,7 +33,7 @@
#include "dml/display_mode_vba.h"
struct _vcs_dpi_ip_params_st dcn3_14_ip = {
- .VBlankNomDefaultUS = 668,
+ .VBlankNomDefaultUS = 800,
.gpuvm_enable = 1,
.gpuvm_max_page_table_levels = 1,
.hostvm_enable = 1,
@@ -286,7 +286,7 @@ int dcn314_populate_dml_pipes_from_context_fpu(struct dc *dc, struct dc_state *c
struct resource_context *res_ctx = &context->res_ctx;
struct pipe_ctx *pipe;
bool upscaled = false;
- bool isFreesyncVideo = false;
+ const unsigned int max_allowed_vblank_nom = 1023;
dc_assert_fp_enabled();
@@ -300,16 +300,11 @@ int dcn314_populate_dml_pipes_from_context_fpu(struct dc *dc, struct dc_state *c
pipe = &res_ctx->pipe_ctx[i];
timing = &pipe->stream->timing;
- isFreesyncVideo = pipe->stream->adjust.v_total_max == pipe->stream->adjust.v_total_min;
- isFreesyncVideo = isFreesyncVideo && pipe->stream->adjust.v_total_min > timing->v_total;
-
- if (!isFreesyncVideo) {
- pipes[pipe_cnt].pipe.dest.vblank_nom =
- dcn3_14_ip.VBlankNomDefaultUS / (timing->h_total / (timing->pix_clk_100hz / 10000.0));
- } else {
- pipes[pipe_cnt].pipe.dest.vtotal = pipe->stream->adjust.v_total_min;
- pipes[pipe_cnt].pipe.dest.vblank_nom = timing->v_total - pipes[pipe_cnt].pipe.dest.vactive;
- }
+ pipes[pipe_cnt].pipe.dest.vtotal = pipe->stream->adjust.v_total_min;
+ pipes[pipe_cnt].pipe.dest.vblank_nom = timing->v_total - pipes[pipe_cnt].pipe.dest.vactive;
+ pipes[pipe_cnt].pipe.dest.vblank_nom = min(pipes[pipe_cnt].pipe.dest.vblank_nom, dcn3_14_ip.VBlankNomDefaultUS);
+ pipes[pipe_cnt].pipe.dest.vblank_nom = max(pipes[pipe_cnt].pipe.dest.vblank_nom, timing->v_sync_width);
+ pipes[pipe_cnt].pipe.dest.vblank_nom = min(pipes[pipe_cnt].pipe.dest.vblank_nom, max_allowed_vblank_nom);
if (pipe->plane_state &&
(pipe->plane_state->src_rect.height < pipe->plane_state->dst_rect.height ||
