[PATCH] drm/amd/display: Shorten delay time to 1us while resetting FIFO

[Liu, Zhan]

[Public]

Apologize for sending out the patch with the wrong sensitivity a few seconds ago. I've updated sensitivity policy to "Public" here.

Thanks,
Zhan

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Liu, Zhan
> Sent: 2022/January/19, Wednesday 5:19 PM
> To: amd-gfx at lists.freedesktop.org
> Cc: Liu, Charlene <Charlene.Liu at amd.com>; Kotarac, Pavle
> <Pavle.Kotarac at amd.com>; Pierre-Loup Griffais <pgriffais at valvesoftware.com>;
> Gutierrez, Agustin <Agustin.Gutierrez at amd.com>; Cornij, Nikola
> <Nikola.Cornij at amd.com>
> Subject: [PATCH] drm/amd/display: Shorten delay time to 1us while resetting FIFO
>
> [Why]
> Current FIFO reset delay for dcn10 is 100us, which is too long and will fail atomic
> flip. As a result, there will be no display on boot.
>
> [How]
> Shorten delay time to 1us. This also aligns with FIFO reset delay on other ASICs.
>
> Signed-off-by: Zhan Liu <zhan.liu at amd.com>
> ---
>  drivers/gpu/drm/amd/display/dc/dcn10/dcn10_stream_encoder.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_stream_encoder.c
> b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_stream_encoder.c
> index bf4436d7aaab..2077c22befa5 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_stream_encoder.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_stream_encoder.c
> @@ -909,7 +909,7 @@ void enc1_stream_encoder_reset_fifo(
>
>         /* set DIG_START to 0x1 to reset FIFO */
>         REG_UPDATE(DIG_FE_CNTL, DIG_START, 1);
> -       udelay(100);
> +       udelay(1);
>
>         /* write 0 to take the FIFO out of reset */
>         REG_UPDATE(DIG_FE_CNTL, DIG_START, 0);
> --
> 2.25.1