On Tue, Nov 25, 2014 at 10:25 PM, Dave Airlie airlied@gmail.com wrote:
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.
v1.1: fixup comment (Tom).
Signed-off-by: Dave Airlie airlied@redhat.com
Acked-by: Alex Deucher alexander.deucher@amd.com
drivers/gpu/drm/drm_dp_helper.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 959e207..79968e3 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -186,10 +186,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
/* * The specification doesn't give any recommendation on how often to
* retry native transactions, so retry 7 times like for I2C-over-AUX* transactions.
* retry native transactions. We used to retry 7 times like for* aux i2c transactions but real world devices this wasn't* sufficient, bump to 32 which makes Dell 4k monitors happier. */
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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