[Intel-gfx] [PATCH 1/2] drm/dp: retry AUX transactions 32 times

[Tom Stellard]

On Wed, Nov 26, 2014 at 01:17:22PM +1000, Dave Airlie wrote:
> From: Dave Airlie <airlied at redhat.com>
> 
> At least on two MST devices I've tested with, when
> they are link training downstream, they are totally
> unable to handle aux ch msgs, so they defer like nuts.
> I tried 16, it wasn't enough, 32 seems better.
> 
> This fixes one Dell 4k monitor and one of the
> MST hubs.
> 
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 959e207..db0993f 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -189,7 +189,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
>  	 * retry native transactions, so retry 7 times like for I2C-over-AUX

Should this comment be updated too?

-Tom

>  	 * transactions.
>  	 */
> -	for (retry = 0; retry < 7; retry++) {
> +	for (retry = 0; retry < 32; retry++) {
>  
>  		mutex_lock(&aux->hw_mutex);
>  		err = aux->transfer(aux, &msg);
> -- 
> 2.1.0
> 
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