[PATCH] drm/amd/display: Fix dsc mismatch of acquire and validationn of dsc engine

[Wu, Hersen]

[AMD Official Use Only - General]

Reviewed-by: Hersen Wu <Hersenxs.Wu at amd.com>

Regards!
Hersen


-----Original Message-----
From: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com> 
Sent: Wednesday, December 21, 2022 1:44 PM
To: Swarnakar, Praful <Praful.Swarnakar at amd.com>; Wu, Hersen <hersenxs.wu at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>
Cc: amd-gfx at lists.freedesktop.org; Lakha, Bhawanpreet <Bhawanpreet.Lakha at amd.com>; Liu, Wenjing <Wenjing.Liu at amd.com>
Subject: [PATCH] drm/amd/display: Fix dsc mismatch of acquire and validationn of dsc engine

[Why]
We skip dsc_validation on pipes that are underlays, but in the acquire_dsc code we don't have this check.

In certain conditions (when underlay pipe index is lower) we will assign the dsc resource to the underlay pipe and skip the base pipe.

Now during dsc_validation we will skip the underlay pipe (this has the dsc resource) but try to validate the base pipe(this doesn't have a dsc
resource) due to this mismatch we hit a NULLPTR

[How]
In the acquire_dsc add a check for underlay pipe so we don't acquire a dsc resource for this pipe. This will match the acquire/validation conditions.

Reviewed-by: Wenjing Liu <Wenjing.Liu at amd.com>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c | 3 +++
 1 file changed, 3 insertions(+)

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 d0199ec045cb..f97d8ff16e71 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
@@ -1382,6 +1382,9 @@ enum dc_status dcn20_add_dsc_to_stream_resource(struct dc *dc,
 	for (i = 0; i < dc->res_pool->pipe_count; i++) {
 		struct pipe_ctx *pipe_ctx = &dc_ctx->res_ctx.pipe_ctx[i];
 
+		if (pipe_ctx->top_pipe)
+			continue;
+
 		if (pipe_ctx->stream != dc_stream)
 			continue;
 
--
2.25.1