On Wed, 26 Nov 2014, Dave Airlie <airlied at gmail.com> 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. > > v1.1: fixup comment (Tom).
Missed this version, see my reply to v1: http://mid.gmane.org/87k32iqppg.fsf at intel.com Also, what if you avoid sink dpms off with: diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 70bb8d0b9695..768b1bfaea78 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1932,7 +1932,7 @@ void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode) if (mode != DRM_MODE_DPMS_ON) { ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, - DP_SET_POWER_D3); + DP_SET_POWER_D0); } else { /* * When turning on, we need to retry for 1ms to give the sink Does it make a difference? BR, Jani. > > Signed-off-by: Dave Airlie <airlied at redhat.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 > > _______________________________________________ > dri-devel mailing list > dri-devel at lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel -- Jani Nikula, Intel Open Source Technology Center
