AMD General
Hi Mauricio:
This change breaks dsc, causing black screen.
Sink RX dsc enable should land after link training. Writing dsc enable to
the RX on an untrained link is too early, that should be done after training.
That is likely to be the main sequence regression.
Regards,
Jerry
> -----Original Message-----
> From: amd-gfx <[email protected]> On Behalf Of
> Mauricio Bellon
> Sent: Tuesday, August 25, 2026 17:18
> To: [email protected]
> Cc: Lin, Wayne <[email protected]>; Limonciello, Mario
> <[email protected]>; Mauricio Bellon <[email protected]>;
> Wentland, Harry <[email protected]>; Li, Sun peng (Leo)
> <[email protected]>; Rodrigo Siqueira <[email protected]>; Deucher,
> Alexander <[email protected]>; Koenig, Christian
> <[email protected]>; [email protected]
> Subject: [PATCH 2/2] drm/amd/display: enable sink DSC before source DSC
>
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>
> From: Mauricio Bellon <[email protected]>
>
> Direct DisplayPort high-refresh modes using DSC and two-way ODM can
> commit without visible output during a 4K120-to-4K144 transition. A working
> 4K144 stream can also return black after long-pulse hotplug reconstruction.
>
> The DPMS-on path currently enables source DSC before link enablement but
> does not enable sink DSC until after the source stream is enabled. This leaves
> the sink and source compression state ordered differently while the stream is
> brought up.
>
> Enable sink DSC immediately before source DSC in the pre-enable phase, and
> remove the later redundant sink-enable operation near PPS packet
> programming. This establishes the order as sink DSC, source DSC, stream
> enablement, and PPS before the compressed stream becomes visible.
>
> Cc: [email protected]
> Signed-off-by: Mauricio Bellon <[email protected]>
> ---
> drivers/gpu/drm/amd/display/dc/link/link_dpms.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
> b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
> index 48b086d15..412ce52b3 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
> +++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
> @@ -2635,8 +2635,10 @@ static enum dc_status
> link_set_dpms_on_pre_enable_link(
> */
> if (stream->timing.flags.DSC) {
> if (dc_is_dp_signal(stream->signal) ||
> - dc_is_virtual_signal(stream->signal))
> + dc_is_virtual_signal(stream->signal)) {
> + dp_set_dsc_on_rx(pipe_ctx, true);
> link_set_dsc_enable(pipe_ctx, true);
> + }
> }
>
> if (link->replay_settings.config.replay_supported
> && !dc_is_embedded_signal(link->connector_signal))
> @@ -2729,7 +2731,6 @@ static enum dc_status
> link_set_dpms_on_post_enable_link(
> if (stream->timing.flags.DSC) {
> if (dc_is_dp_signal(stream->signal) ||
> dc_is_virtual_signal(stream->signal)) {
> - dp_set_dsc_on_rx(pipe_ctx, true);
> link_set_dsc_pps_packet(pipe_ctx, true, true);
> }
> }
> --
> 2.53.0
