On Thu, 6 Mar 2014 11:28:13 +0200
Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> On Wed, Mar 05, 2014 at 02:48:30PM -0800, Jesse Barnes wrote:
> > It takes awhile to fetch the DPCD and EDID for caching, so take it out
> > of the critical path to improve init time.
> >
> > Signed-off-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_dp.c | 113 +++++++++++++++++++++++++++++-----------
> > 1 file changed, 82 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 738c4e6..763f235 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -3001,6 +3001,20 @@ intel_dp_handle_test_request(struct intel_dp *intel_dp)
> > intel_dp_aux_native_write_1(intel_dp, DP_TEST_RESPONSE, DP_TEST_NAK);
> > }
> >
> > +static void intel_flush_edp_cache_work(struct intel_dp *intel_dp)
> > +{
> > + struct drm_device *dev = intel_dp->attached_connector->base.dev;
> > +
> > + WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
> > +
> > + if (!is_edp(intel_dp))
> > + return;
> > +
> > + mutex_unlock(&dev->mode_config.mutex);
> > + flush_work(&intel_dp->edp_cache_work);
> > + mutex_lock(&dev->mode_config.mutex);
>
> This feels like deadlock land to me. If we drop mode_config.mutex
> someone else might grab it and then get blocked on the crtc mutex
> we're already holding, and then we try to re-grab mode_config.mutex...
Yeah I could use unlock_all here instead, or be more careful about
dropping the specific crtc mutex we need. I did that on the crtc side
of things but obviously missed it here for cases where we'll hold the
crtc lock in this path.
--
Jesse Barnes, Intel Open Source Technology Center
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