On Thu, Jul 28, 2016 at 12:48:53PM -0700, Manasi Navare wrote:
> On Thu, Jul 28, 2016 at 05:50:43PM +0300, [email protected] wrote:
> > From: Ville Syrjälä <[email protected]>
> >
> > DP link retraining needs to grab some modeset locks to not race with
> > modesets, so we can't really do it safely from the hpd_pulse, lest we
> > risk deadlocking due to MST sideband stuff.
> >
> > Move the link retraining to happen from the hotplug work instead.
> > Doing at the end of intel_dp_detect() seems like a good place in case
> > the sink already got disconnected, in which case retraining is
> > pointless.
> >
> > To determine if we need to schedule the hotplug work, we'll just check
> > the sink lane status without locks from hpd_pulse. A little racy
> > still eg. due to useing intel_dp->lane_count, but no less racy than
> > what we already had. We'll repeat the check in from intel_dp_detect()
> > with proper locking, where we'll also check if the link as actually
> > active or not.
> >
> > Cc: Ander Conselvan de Oliveira <[email protected]>
> > Cc: Jim Bride <[email protected]>
> > Cc: Manasi D Navare <[email protected]>
> > Cc: Durgadoss R <[email protected]>
> > Signed-off-by: Ville Syrjälä <[email protected]>
> > ---
> > drivers/gpu/drm/i915/intel_dp.c | 154
> > +++++++++++++++++-----------------------
> > 1 file changed, 66 insertions(+), 88 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index 4a4184c21989..675b83f57a07 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -3842,15 +3842,6 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
> > bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> > go_again:
> > if (bret == true) {
> > -
> > - /* check link status - esi[10] = 0x200c */
> > - if (intel_dp->active_streams &&
> > - !drm_dp_channel_eq_ok(&esi[10],
> > intel_dp->lane_count)) {
> > - DRM_DEBUG_KMS("channel EQ not ok,
> > retraining\n");
> > - intel_dp_start_link_train(intel_dp);
> > - intel_dp_stop_link_train(intel_dp);
> > - }
> > -
> > DRM_DEBUG_KMS("got esi %3ph\n", esi);
> > ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi,
> > &handled);
> >
> > @@ -3886,34 +3877,42 @@ go_again:
> > return -EINVAL;
> > }
> >
> > -static void
> > -intel_dp_check_link_status(struct intel_dp *intel_dp)
> > +static bool
> > +intel_dp_link_needs_retrain(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];
> >
> > - WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> > + if (intel_dp->active_streams == 0)
> > + return false;
> > +
> > + if (intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING)
> > + return true;
> >
> > if (!intel_dp_get_link_status(intel_dp, link_status)) {
> > DRM_ERROR("Failed to get link status\n");
> > - return;
> > + return false;
> > }
> >
> > - if (!intel_encoder->base.crtc)
> > - return;
> > + return !drm_dp_channel_eq_ok(link_status, intel_dp->lane_count);
>
> According to the DP spec, we should also check for the clock recovery bit in
> DPCD
> We should also add a check drm_dp_clock_recovery_ok(link_status,
> intel_dp->lane_count)
I think drm_dp_channel_eq_ok() checks all the bits: INTERLANE_ALIGN_DONE,
CR_DONE, EQ_DONE, and SYMBOL_LOCKED.
Anyways, while I was looking at the short pulse handling a bit more, I came
to the conclusion that we should rewrite it a bit.
The CTS docs seem to say that we're expected to read DPCD 0x200-0x205 on
short pulse, and use that information to determine what we should do.
Currently we don't do that.
So I was thunking that we'd adjust the link_status stuff to read 0x200-0x207
instead of 0x202-0x207, like so:
-#define DP_LINK_STATUS_SIZE 6
+#define DP_LINK_STATUS_SIZE 8
static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
{
- return link_status[r - DP_LANE0_1_STATUS];
+ return link_status[r - DP_SINK_COUNT];
}
And then we'd use something like this as our short pulse handler:
static bool
intel_dp_short_pulse(struct intel_dp *intel_dp)
{
u8 link_status[DP_LINK_STATUS_SIZE], tmp;
/*
* Clearing compliance test variables to allow capturing
* of values for next automated test request.
*/
intel_dp->compliance_test_active = 0;
intel_dp->compliance_test_type = 0;
intel_dp->compliance_test_data = 0;
if (!intel_dp_get_link_status(intel_dp, link_status))
return false;
tmp = drm_dp_link_status(link_status, DP_DEVICE_SERVICE_IRQ_VECTOR);
if (tmp)
drm_dp_dpcd_writeb(&intel_dp->aux,
DP_DEVICE_SERVICE_IRQ_VECTOR,
tmp);
if (tmp & DP_AUTOMATED_TEST_REQUEST)
DRM_DEBUG_DRIVER("Test request in short pulse not handled\n");
if (tmp & (DP_CP_IRQ | DP_SINK_SPECIFIC_IRQ))
DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
tmp = drm_dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
if (tmp & DP_DOWNSTREAM_PORT_STATUS_CHANGED)
return false;
tmp = drm_dp_link_status(link_status, DP_SINK_COUNT);
if (DP_GET_SINK_COUNT(tmp) != intel_dp->sink_count)
return false;
if (intel_dp->active_streams != 0 &&
!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))
return false;
return true;
}
and obviously fill in whatever else sink irq handling we need.
Thoughts? Does that look sane?
<snip>
> >
> > static enum drm_connector_status
> > intel_dp_detect(struct drm_connector *connector, bool force)
> > {
> > struct intel_dp *intel_dp = intel_attached_dp(connector);
> > - struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> > - struct intel_encoder *intel_encoder = &intel_dig_port->base;
> > struct intel_connector *intel_connector = to_intel_connector(connector);
> > + enum drm_connector_status status;
> >
> > DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
> > connector->base.id, connector->name);
> >
> > - if (intel_dp->is_mst) {
> > - /* MST devices are disconnected from a monitor POV */
> > - intel_dp_unset_edid(intel_dp);
> > - if (intel_encoder->type != INTEL_OUTPUT_EDP)
> > - intel_encoder->type = INTEL_OUTPUT_DP;
> > - return connector_status_disconnected;
> > - }
> > -
> > - /* If full detect is not performed yet, do a full detect */
> > - if (!intel_dp->detect_done)
> > - intel_dp_long_pulse(intel_dp->attached_connector);
> > + status = intel_dp_long_pulse(intel_connector);
> >
> > - intel_dp->detect_done = false;
> > + if (status == connector_status_connected || intel_dp->is_mst)
>
> Whya re we not checking for (!intel_encoder->crtc.base) before retraining?
> I had seen issues with connected boot case when connector status is connected
> and if it
> tries to retrain it fails with retries because there is no active pipe. In
> that
> case it should not attempt to retrain.
I changed it to use intel_dp->active_streams instead. That'll work for MST
as well as SST. Checking for the crtc would only cover SST.
>
>
> > + intel_dp_link_retrain(intel_dp);
> >
> > - if (is_edp(intel_dp) || intel_connector->detect_edid)
> > - return connector_status_connected;
> > - else
> > - return connector_status_disconnected;
> > + return status;
> > }
> >
> > static void
> > @@ -4706,39 +4682,41 @@ intel_dp_hpd_pulse(struct intel_digital_port
> > *intel_dig_port, bool long_hpd)
> > port_name(intel_dig_port->port),
> > long_hpd ? "long" : "short");
> >
> > + if (long_hpd)
> > + return IRQ_NONE;
> > +
> > power_domain = intel_display_port_aux_power_domain(intel_encoder);
> > intel_display_power_get(dev_priv, power_domain);
> >
> > - if (long_hpd) {
> > - intel_dp_long_pulse(intel_dp->attached_connector);
> > - if (intel_dp->is_mst)
> > - ret = IRQ_HANDLED;
> > - goto put_power;
> > -
> > - } else {
> > - if (intel_dp->is_mst) {
> > - if (intel_dp_check_mst_status(intel_dp) == -EINVAL) {
> > - /*
> > - * If we were in MST mode, and device is not
> > - * there, get out of MST mode
> > - */
> > - DRM_DEBUG_KMS("MST device may have disappeared
> > %d vs %d\n",
> > - intel_dp->is_mst,
> > intel_dp->mst_mgr.mst_state);
> > - intel_dp->is_mst = false;
> > -
> > drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,
> > -
> > intel_dp->is_mst);
> > - goto put_power;
> > - }
> > - }
> > -
> > - if (!intel_dp->is_mst) {
> > - if (!intel_dp_short_pulse(intel_dp)) {
> > -
> > intel_dp_long_pulse(intel_dp->attached_connector);
> > - goto put_power;
> > - }
> > + if (intel_dp->is_mst) {
> > + if (intel_dp_check_mst_status(intel_dp) == -EINVAL) {
> > + /*
> > + * If we were in MST mode, and device is not
> > + * there, get out of MST mode
> > + */
> > + DRM_DEBUG_KMS("MST device may have disappeared %d vs
> > %d\n",
> > + intel_dp->is_mst,
> > intel_dp->mst_mgr.mst_state);
> > + intel_dp->is_mst = false;
> > + drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,
> > + intel_dp->is_mst);
> > + goto put_power;
> > }
> > + } else {
> > + if (!intel_dp_short_pulse(intel_dp))
> > + goto put_power;
> > }
> >
> > + /*
> > + * Link retraining happens from the hotplug work,
> > + * check if we might need to schdule it.
> > + *
> > + * There has been known issues of link loss
> > + * triggerring long pulse, so let's check both
> > + * for short and long pulse.
> > + */
> > + if (intel_dp_link_needs_retrain(intel_dp))
> > + goto put_power;
> > +
> > ret = IRQ_HANDLED;
> >
> > put_power:
> > --
> > 2.7.4
> >
--
Ville Syrjälä
Intel OTC
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