Op 09-02-17 om 13:34 schreef Ville Syrjälä:
> On Thu, Feb 09, 2017 at 12:27:12PM +0100, Maarten Lankhorst wrote:
>> Op 26-01-17 om 19:31 schreef Ville Syrjälä:
>>> On Mon, Jan 09, 2017 at 06:06:57PM +0100, Maarten Lankhorst wrote:
>>>> We're protected by the connection_mutex lock against blocking modesets,
>>>> but nonblocking modesets are performed without any locking. This is
>>>> causing WARN in drm_wait_for_vblank and in general it's better to wait
>>>> before modeset completes before trying anything.
>>>>
>>>> Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
>>>> ---
>>>> drivers/gpu/drm/i915/intel_dp.c | 51
>>>> +++++++++++++++++++++++++++++++----------
>>>> 1 file changed, 39 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c
>>>> b/drivers/gpu/drm/i915/intel_dp.c
>>>> index fb12896bafee..71882d887393 100644
>>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>>> @@ -4080,24 +4080,38 @@ intel_dp_check_link_status(struct intel_dp
>>>> *intel_dp)
>>>> struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
>>>> struct drm_device *dev = intel_dp_to_dev(intel_dp);
>>>> u8 link_status[DP_LINK_STATUS_SIZE];
>>>> + struct drm_modeset_acquire_ctx ctx;
>>>> + struct intel_connector *intel_connector = intel_dp->attached_connector;
>>>> + int ret;
>>>> + struct drm_crtc *crtc;
>>>>
>>>> - WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>>>> + drm_modeset_acquire_init(&ctx, 0);
>>>> +
>>>> +retry:
>>>> + ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
>>>> + if (ret)
>>>> + goto out;
>>>>
>>>> if (!intel_dp_get_link_status(intel_dp, link_status)) {
>>>> DRM_ERROR("Failed to get link status\n");
>>>> - return;
>>>> + goto out;
>>>> }
>>>>
>>>> - if (!intel_encoder->base.crtc)
>>>> - return;
>>>> + crtc = intel_connector->base.state->crtc;
>>>> + if (!crtc)
>>>> + goto out;
>>>>
>>>> - if (!to_intel_crtc(intel_encoder->base.crtc)->active)
>>>> - return;
>>>> + ret = drm_modeset_lock(&crtc->mutex, &ctx);
>>>> + if (ret)
>>>> + goto out;
>>>> +
>>>> + if (!crtc->state->active)
>>>> + goto out;
>>>>
>>>> /* FIXME: we need to synchronize this sort of stuff with hardware
>>>> * readout. Currently fast link training doesn't work on boot-up. */
>>>> if (!intel_dp->lane_count)
>>>> - return;
>>>> + goto out;
>>>>
>>>> /* if link training is requested we should perform it always */
>>>> if ((intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) ||
>>>> @@ -4105,8 +4119,26 @@ intel_dp_check_link_status(struct intel_dp
>>>> *intel_dp)
>>>> DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
>>>> intel_encoder->base.name);
>>>>
>>>> + if (drm_atomic_crtc_needs_modeset(crtc->state)) {
>>>> + /* wait for atomic modeset to complete */
>>>> + ret = drm_atomic_helper_wait_for_hw_done(crtc);
>>>> + if (ret < 0)
>>>> + DRM_ERROR("Waiting for hw_done timed out\n");
>>> I wonder if we should just skip the hw frobbing in this case. I guess it
>>> might still restore the link if the commit just somehow got stuck
>>> somewhere non-critical.
>> Hm, we could check if the link training is still required after the wait.
>> Maybe even do the wait unlocked, since it might take an arbitrary amount of
>> time
>> and then retry?
> I'm not sure there's much point in trying to make this fancy. Link
> problems should not happen with any regularity.
Indeed, lets just do the simple thing then.
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