Patch "drm/amd/display: Map DSC resources 1-to-1 if numbers of OPPs and DSCs are equal" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: Map DSC resources 1-to-1 if numbers of OPPs and DSCs are equal

to the 5.4-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-map-dsc-resources-1-to-1-if-numbers-.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c0a5f0491459e1f6e383355df62ca06d0183a7e0
Author: Nikola Cornij <nikola.cornij@xxxxxxx>
Date:   Thu Nov 7 13:06:48 2019 -0500

    drm/amd/display: Map DSC resources 1-to-1 if numbers of OPPs and DSCs are equal
    
    [ Upstream commit a1fc44b609b4e9c0941f0e4a1fc69d367af5ab69 ]
    
    [why]
    On ASICs where number of DSCs is the same as OPPs there's no need
    for DSC resource management. Mappping 1-to-1 fixes mode-set- or S3-
    -related issues for such platforms.
    
    [how]
    Map DSC resources 1-to-1 to pipes only if number of OPPs is the same
    as number of DSCs. This will still keep other ASICs working.
    A follow-up patch to fix mode-set issues on those ASICs will be
    required if testing shows issues with mode set.
    
    Signed-off-by: Nikola Cornij <nikola.cornij@xxxxxxx>
    Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@xxxxxxx>
    Acked-by: Leo Li <sunpeng.li@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
index 78b2cc2e122f..3b7769a3e67e 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
@@ -1419,13 +1419,20 @@ enum dc_status dcn20_build_mapped_resource(const struct dc *dc, struct dc_state
 
 static void acquire_dsc(struct resource_context *res_ctx,
 			const struct resource_pool *pool,
-			struct display_stream_compressor **dsc)
+			struct display_stream_compressor **dsc,
+			int pipe_idx)
 {
 	int i;
 
 	ASSERT(*dsc == NULL);
 	*dsc = NULL;
 
+	if (pool->res_cap->num_dsc == pool->res_cap->num_opp) {
+		*dsc = pool->dscs[pipe_idx];
+		res_ctx->is_dsc_acquired[pipe_idx] = true;
+		return;
+	}
+
 	/* Find first free DSC */
 	for (i = 0; i < pool->res_cap->num_dsc; i++)
 		if (!res_ctx->is_dsc_acquired[i]) {
@@ -1468,7 +1475,7 @@ static enum dc_status add_dsc_to_stream_resource(struct dc *dc,
 		if (pipe_ctx->stream != dc_stream)
 			continue;
 
-		acquire_dsc(&dc_ctx->res_ctx, pool, &pipe_ctx->stream_res.dsc);
+		acquire_dsc(&dc_ctx->res_ctx, pool, &pipe_ctx->stream_res.dsc, i);
 
 		/* The number of DSCs can be less than the number of pipes */
 		if (!pipe_ctx->stream_res.dsc) {
@@ -1669,7 +1676,7 @@ static bool dcn20_split_stream_for_odm(
 	next_odm_pipe->stream_res.opp = pool->opps[next_odm_pipe->pipe_idx];
 #ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
 	if (next_odm_pipe->stream->timing.flags.DSC == 1) {
-		acquire_dsc(res_ctx, pool, &next_odm_pipe->stream_res.dsc);
+		acquire_dsc(res_ctx, pool, &next_odm_pipe->stream_res.dsc, next_odm_pipe->pipe_idx);
 		ASSERT(next_odm_pipe->stream_res.dsc);
 		if (next_odm_pipe->stream_res.dsc == NULL)
 			return false;