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drm/amd/display: Fix USB4 null pointer dereference in update_psp_stream_config

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[Why]
A porting error on a previous patch left the block of code that
causes the crash from a NULL pointer dereference.

More specifically, we try to access link_enc before it's assigned in
the USB4 case in the following assignment:

config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A;

[How]
That assignment occurs later depending on the ASIC version. It's only
needed on DCN31 and only after link_enc is already assigned.

Fixes: 986430446c ("drm/amd/display: fix a crash on USB4 over C20 PHY")
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Nicholas Kazlauskas 2021-12-17 14:18:59 -05:00 committed by Alex Deucher
parent 33735c1c8d
commit 33bb63915f
1 changed files with 1 additions and 4 deletions
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5
drivers/gpu/drm/amd/display/dc/core/dc_link.c
View File

@ -3945,12 +3945,9 @@ static void update_psp_stream_config(struct pipe_ctx *pipe_ctx, bool dpms_off)
config.dig_be = pipe_ctx->stream->link->link_enc_hw_inst;
#if defined(CONFIG_DRM_AMD_DC_DCN)
config.stream_enc_idx = pipe_ctx->stream_res.stream_enc->id - ENGINE_ID_DIGA;
if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY ||
pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA) {
link_enc = pipe_ctx->stream->link->link_enc;
config.dio_output_type = pipe_ctx->stream->link->ep_type;
config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A;
if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY)
link_enc = pipe_ctx->stream->link->link_enc;
else if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)