[PATCH] drm/amd/display: re-enable wait in pipelock, but add timeout

[Harry Wentland]

On 2019-11-15 11:01 a.m., Alex Deucher wrote:
> Removing this causes hangs in some games, so re-add it, but add
> a timeout so we don't hang while switching flip types.
> 
> Bug: https://bugzilla.kernel.org/show_bug.cgi?id=205169
> Bug: https://bugs.freedesktop.org/show_bug.cgi?id=112266
> Bug: https://bugzilla.kernel.org/show_bug.cgi?id=205169
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>

Patch is
Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>  .../drm/amd/display/dc/dcn20/dcn20_hwseq.c    | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
> index 0046a099c9e9..120e62c5193c 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
> @@ -1033,6 +1033,25 @@ void dcn20_pipe_control_lock(
>  	if (pipe->plane_state != NULL)
>  		flip_immediate = pipe->plane_state->flip_immediate;
>  
> +	if (flip_immediate && lock) {
> +		const int TIMEOUT_FOR_FLIP_PENDING = 100000;
> +		int i;
> +
> +		for (i = 0; i < TIMEOUT_FOR_FLIP_PENDING; ++i) {
> +			if (!pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->plane_res.hubp))
> +				break;
> +			udelay(1);
> +		}
> +
> +		if (pipe->bottom_pipe != NULL) {
> +			for (i = 0; i < TIMEOUT_FOR_FLIP_PENDING; ++i) {
> +				if (!pipe->bottom_pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->bottom_pipe->plane_res.hubp))
> +					break;
> +				udelay(1);
> +			}
> +		}
> +	}
> +
>  	/* In flip immediate and pipe splitting case, we need to use GSL
>  	 * for synchronization. Only do setup on locking and on flip type change.
>  	 */
>