From: Dave Airlie airlied@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@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 * transactions. */ - for (retry = 0; retry < 7; retry++) { + for (retry = 0; retry < 32; retry++) {
mutex_lock(&aux->hw_mutex); err = aux->transfer(aux, &msg);