[PATCH] drm/amd/display: Keep eDP Vdd on when eDP stream is already

[Liu, Zhan]

[Public]

After giving it a second thought, I will apply a similar patch on internal branch first, then get it promoted to external branch. This patch is abandoned.

Thanks,
Zhan

> -----Original Message-----
> From: Liu, Zhan
> Sent: 2022/January/27, Thursday 9:51 PM
> To: amd-gfx at lists.freedesktop.org; Liu, Charlene <Charlene.Liu at amd.com>
> Cc: Pierre-Loup Griffais <pgriffais at valvesoftware.com>; Cornij, Nikola
> <Nikola.Cornij at amd.com>; Kotarac, Pavle <Pavle.Kotarac at amd.com>; Gutierrez,
> Agustin <Agustin.Gutierrez at amd.com>
> Subject: [PATCH] drm/amd/display: Keep eDP Vdd on when eDP stream is already
>
> [Why]
> Even if can_apply_edp_fast_boot is set to 1 at boot, this flag will be cleared to 0
> at S3 resume. However, we still need to keep Vdd on at S3 resume. Turning eDP
> Vdd off at resume will result in black screen at S3 resume.
>
> [How]
> Don't turn eDP Vdd off when there is an existing eDP stream. This can assure eDP
> display come back after S3.
>
> Signed-off-by: Zhan Liu <zhan.liu at amd.com>
> ---
>  .../display/dc/dce110/dce110_hw_sequencer.c   | 23 +++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> index 72dd41e7a7d6..1aa6f2737534 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> @@ -1796,9 +1796,28 @@ void dce110_enable_accelerated_mode(struct dc *dc,
> struct dc_state *context)
>                               break;
>                       }
>               }
> -             // We are trying to enable eDP, don't power down VDD
> -             if (can_apply_edp_fast_boot)
> +
> +             /*
> +              * TO-DO: So far the code logic below only addresses single eDP
> case.
> +              * For dual eDP case, there are a few things that need to be
> +              * implemented first:
> +              *
> +              * 1. Change the fastboot logic above, so eDP link[0 or 1]'s
> +              * stream[0 or 1] will all be checked.
> +              *
> +              * 2. Change keep_edp_vdd_on to an array, and maintain
> keep_edp_vdd_on
> +              * for each eDP.
> +              *
> +              * Once above 2 things are completed, we can then change the
> logic below
> +              * correspondingly, so dual eDP case will be fully covered.
> +              */
> +
> +             // We are trying to enable eDP, don't power down VDD if there is
> an existing eDP stream
> +             if ((edp_stream_num = 1 && edp_streams[0]) ||
> +can_apply_edp_fast_boot) {
>                       keep_edp_vdd_on = true;
> +                     DC_LOG_EVENT_LINK_TRAINING("At least 1 eDP stream is
> already enabled, will keep eDP Vdd on\n");
> +             } else
> +                     DC_LOG_EVENT_LINK_TRAINING("No eDP stream enabled,
> will turn eDP Vdd
> +off\n");
>       }
>
>       // Check seamless boot support
> --
> 2.25.1