[Intel-gfx] [PATCH v10] drm/i915: Implement Link Rate fallback on Link training failure
Jani Nikula
jani.nikula at intel.com
Fri Mar 31 10:33:04 UTC 2017
On Fri, 31 Mar 2017, Manasi Navare <manasi.d.navare at intel.com> wrote:
> Hi Jani,
>
> I have reviewed your recent DP link rate / lane count
> refactoring patch series and I believe that it will soon get merged.
I haven't received reviews on all of the patches in my series yet, in
particular the first patches are missing reviews so I can't even get
started pushing them.
BR,
Jani.
>
> Are you waiting on merging this patch so that your refactoring
> series gets merged first? Or can we merge this patch since
> it already has ACKs and R-bs.
>
> Please advise on next steps for this patch, since some
> of the PSR related patches are pending merge because of this.
>
> Regards
> Manasi
>
>
> On Wed, Mar 22, 2017 at 08:44:36AM -0700, Manasi Navare wrote:
>> Hi Jani/Ville,
>>
>> I need to add another quick fix which would be required for the fallback
>> to happen as expected. Should I respin this patch to add that fix or
>> should I wait for this to get landed?
>>
>> I have mentioned the fix suggested below, please let me know your thoughts on that.
>>
>>
>> On Tue, Mar 14, 2017 at 03:11:51PM -0700, Manasi Navare wrote:
>> > If link training at a link rate optimal for a particular
>> > mode fails during modeset's atomic commit phase, then we
>> > let the modeset complete and then retry. We save the link rate
>> > value at which link training failed, update the link status property
>> > to "BAD" and use a lower link rate to prune the modes. It will redo
>> > the modeset on the current mode at lower link rate or if the current
>> > mode gets pruned due to lower link constraints then, it will send a
>> > hotplug uevent for userspace to handle it.
>> >
>> > This is also required to pass DP CTS tests 4.3.1.3, 4.3.1.4,
>> > 4.3.1.6.
>> >
>> > This patch is a resend of the original commit id (233ce881dd91fb
>> > "drm/i915: Implement Link Rate fallback on Link training failure")
>> > which got reverted in this commit id (afc1ebf4562a14 Revert
>> > "drm/i915: Implement Link Rate fallback on Link training failure")
>> > due to CI failures.
>> >
>> > After investigating the CI failures it was found that these
>> > were essentially the failures which were always there but hidden because
>> > they used to be DRM_DEBUG_KMS messages for link failures so never got
>> > caught by CI. But now this patch actually throws DRM_ERROR if the link
>> > training fails at RBR and 1 lane. So it caught these link train failures.
>> >
>> > There were two failures:
>> > 1. On SKL 6700k this was because the machine in CI lab is a SKL desktop
>> > without eDP on Port A. But our VBT initialization code in the driver writes
>> > VBT defaults in a way that it always sets DP flag on Port A and this does
>> > not get cleared after parsing the VBT outputs. This has been fixed in
>> > commit id (bb1d132935c2f8 "drm/i915/vbt: split out defaults that are set
>> > when there is no VBT) and (665788572c6410b "drm/i915/vbt: don't propagate
>> > errors from intel_bios_init())
>> >
>> > 2. On ILK-650 desktop - This was happening because of a bad monitor desktop
>> > combination. I switched the monitor in the CI lab and that helped get rid
>> > of the link failures on ILK system.
>> >
>> > v10:
>> > * Rebase on drm-tip and resend after revert
>> > v9:
>> > * Use the trimmed max values of link rate/lane count based on
>> > link train fallback (Daniel Vetter)
>> > v8:
>> > * Set link_status to BAD first and then call mode_valid (Jani Nikula)
>> > v7:
>> > Remove the redundant variable in previous patch itself
>> > v6:
>> > * Obtain link rate index from fallback_link_rate using
>> > the helper intel_dp_link_rate_index (Jani Nikula)
>> > * Include fallback within intel_dp_start_link_train (Jani Nikula)
>> > v5:
>> > * Move set link status to drm core (Daniel Vetter, Jani Nikula)
>> > v4:
>> > * Add fallback support for non DDI platforms too
>> > * Set connector->link status inside set_link_status function
>> > (Jani Nikula)
>> > v3:
>> > * Set link status property to BAd unconditionally (Jani Nikula)
>> > * Dont use two separate variables link_train_failed and link_status
>> > to indicate same thing (Jani Nikula)
>> > v2:
>> > * Squashed a few patches (Jani Nikula)
>> >
>> > Acked-by: Tony Cheng <tony.cheng at amd.com>
>> > Acked-by: Harry Wentland <Harry.wentland at amd.com>
>> > Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> > Cc: Daniel Vetter <daniel.vetter at intel.com>
>> > Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
>> > Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
>> > Reviewed-by: Jani Nikula <jani.nikula at intel.com>
>> > Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>> > ---
>> > drivers/gpu/drm/i915/intel_dp.c | 27 +++++++++++++++++++++++++++
>> > drivers/gpu/drm/i915/intel_dp_link_training.c | 22 ++++++++++++++++++++--
>> > drivers/gpu/drm/i915/intel_drv.h | 3 +++
>> > 3 files changed, 50 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> > index fd96a6c..895f934 100644
>> > --- a/drivers/gpu/drm/i915/intel_dp.c
>> > +++ b/drivers/gpu/drm/i915/intel_dp.c
>> > @@ -5924,6 +5924,29 @@ intel_dp_init_connector_port_info(struct intel_digital_port *intel_dig_port)
>> > }
>> > }
>> >
>> > +static void intel_dp_modeset_retry_work_fn(struct work_struct *work)
>> > +{
>> > + struct intel_connector *intel_connector;
>> > + struct drm_connector *connector;
>> > +
>> > + intel_connector = container_of(work, typeof(*intel_connector),
>> > + modeset_retry_work);
>> > + connector = &intel_connector->base;
>> > + DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
>> > + connector->name);
>> > +
>> > + /* Grab the locks before changing connector property*/
>> > + mutex_lock(&connector->dev->mode_config.mutex);
>> > + /* Set connector link status to BAD and send a Uevent to notify
>> > + * userspace to do a modeset.
>> > + */
>> > + drm_mode_connector_set_link_status_property(connector,
>> > + DRM_MODE_LINK_STATUS_BAD);
>> > + mutex_unlock(&connector->dev->mode_config.mutex);
>> > + /* Send Hotplug uevent so userspace can reprobe */
>> > + drm_kms_helper_hotplug_event(connector->dev);
>> > +}
>> > +
>> > bool
>> > intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>> > struct intel_connector *intel_connector)
>> > @@ -5936,6 +5959,10 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>> > enum port port = intel_dig_port->port;
>> > int type;
>> >
>> > + /* Initialize the work for modeset in case of link train failure */
>> > + INIT_WORK(&intel_connector->modeset_retry_work,
>> > + intel_dp_modeset_retry_work_fn);
>> > +
>> > if (WARN(intel_dig_port->max_lanes < 1,
>> > "Not enough lanes (%d) for DP on port %c\n",
>> > intel_dig_port->max_lanes, port_name(port)))
>> > diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
>> > index 0048b52..955b239 100644
>> > --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
>> > +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
>> > @@ -313,6 +313,24 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp)
>> > void
>> > intel_dp_start_link_train(struct intel_dp *intel_dp)
>> > {
>> > - intel_dp_link_training_clock_recovery(intel_dp);
>> > - intel_dp_link_training_channel_equalization(intel_dp);
>> > + struct intel_connector *intel_connector = intel_dp->attached_connector;
>> > +
>> > + if (!intel_dp_link_training_clock_recovery(intel_dp))
>> > + goto failure_handling;
>> > + if (!intel_dp_link_training_channel_equalization(intel_dp))
>> > + goto failure_handling;
>> > +
>> > + DRM_DEBUG_KMS("Link Training Passed at Link Rate = %d, Lane count = %d",
>> > + intel_dp->link_rate, intel_dp->lane_count);
>> > + return;
>> > +
>> > + failure_handling:
>> > + DRM_DEBUG_KMS("Link Training failed at link rate = %d, lane count = %d",
>> > + intel_dp->link_rate, intel_dp->lane_count);
>> > + if (!intel_dp_get_link_train_fallback_values(intel_dp,
>> > + intel_dp->link_rate,
>> > + intel_dp->lane_count))
>> > + /* Schedule a Hotplug Uevent to userspace to start modeset */
>> > + schedule_work(&intel_connector->modeset_retry_work);
>>
>> This is where the new boolean intel_dp->train_set_valid will have to be set to false on failure.
>> This ensures that we dont end up retraining at the same parameters in intel_dp_check_link_status()
>>
>> So in intel_dp_check-link_status , just before retraining it will add a check,
>> if (!intel_dp->train_set_valid)
>> return;
>>
>> Ville/Jani what are your thoughts on this?
>>
>> Regards
>> Manasi
>>
>> > + return;
>> > }
>> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> > index 51228fe..0fe1ac8 100644
>> > --- a/drivers/gpu/drm/i915/intel_drv.h
>> > +++ b/drivers/gpu/drm/i915/intel_drv.h
>> > @@ -321,6 +321,9 @@ struct intel_connector {
>> > void *port; /* store this opaque as its illegal to dereference it */
>> >
>> > struct intel_dp *mst_port;
>> > +
>> > + /* Work struct to schedule a uevent on link train failure */
>> > + struct work_struct modeset_retry_work;
>> > };
>> >
>> > struct dpll {
>> > --
>> > 2.1.4
>> >
>> _______________________________________________
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--
Jani Nikula, Intel Open Source Technology Center
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