On Mon, Jun 08, 2020 at 01:11:44AM +0300, Souza, Jose wrote:
> On Fri, 2020-06-05 at 12:48 +0300, Imre Deak wrote:
> > Currently MST on a port can get enabled/disabled from the hotplug work
> > and get disabled from the short pulse work in a racy way. Fix this by
> > relying on the MST state checking in the hotplug work and just schedule
> > a hotplug work from the short pulse handler if some problem happened
> > during the MST interrupt handling.
> >
> > This removes the explicit MST disabling in case of an AUX failure, but
> > if AUX fails, then probably the detection will also fail during the
> > scheduled hotplug work and it's not guaranteed that we'll see
> > intermittent errors anyway.
> >
> > While at it also simplify the error checking of the MST interrupt
> > handler.
> >
> > v2:
> > - Convert intel_dp_check_mst_status() to return bool. (Ville)
> > - Change the intel_dp->is_mst check to an assert, since after this patch
> > the condition can't change after we checked it previously.
> > - Document the return value from intel_dp_check_mst_status().
> > v3:
> > - Remove the intel_dp->is_mst check from intel_dp_check_mst_status().
> > There is no point in checking the same condition twice, even though
> > there is a chance that the hotplug work running concurrently changes
> > it.
> >
> > Cc: José Roberto de Souza <jose.souza@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx> (v1)
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_dp.c | 66 ++++++++++---------------
> > 1 file changed, 26 insertions(+), 40 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 55fda074c0ad..42589cae766d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -5556,35 +5556,46 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
> > "Could not write test response to sink\n");
> > }
> >
> > -static int
> > +/**
> > + * intel_dp_check_mst_status - service any pending MST interrupts, check link status
> > + * @intel_dp: Intel DP struct
> > + *
> > + * Read any pending MST interrupts, call MST core to handle these and ack the
> > + * interrupts. Check if the main and AUX link state is ok.
> > + *
> > + * Returns:
> > + * - %true if pending interrupts were serviced (or no interrupts were
> > + * pending) w/o detecting an error condition.
> > + * - %false if an error condition - like AUX failure or a loss of link - is
> > + * detected, which needs servicing from the hotplug work.
> > + */
> > +static bool
> > intel_dp_check_mst_status(struct intel_dp *intel_dp)
> > {
> > struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > - bool need_retrain = false;
> > -
> > - if (!intel_dp->is_mst)
> > - return -EINVAL;
> > + bool link_ok = true;
> >
> > drm_WARN_ON_ONCE(&i915->drm, intel_dp->active_mst_links < 0);
> >
> > for (;;) {
> > u8 esi[DP_DPRX_ESI_LEN] = {};
> > - bool bret, handled;
> > + bool handled;
> > int retry;
> >
> > - bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> > - if (!bret) {
> > + if (!intel_dp_get_sink_irq_esi(intel_dp, esi)) {
> > drm_dbg_kms(&i915->drm,
> > "failed to get ESI - device may have failed\n");
> > - return -EINVAL;
> > + link_ok = false;
> > +
> > + break;
> > }
> >
> > /* check link status - esi[10] = 0x200c */
> > - if (intel_dp->active_mst_links > 0 && !need_retrain &&
> > + if (intel_dp->active_mst_links > 0 && link_ok &&
> > !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
> > drm_dbg_kms(&i915->drm,
> > "channel EQ not ok, retraining\n");
> > - need_retrain = true;
> > + link_ok = false;
> > }
> >
> > drm_dbg_kms(&i915->drm, "got esi %3ph\n", esi);
> > @@ -5604,7 +5615,7 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
> > }
> > }
> >
> > - return need_retrain;
> > + return link_ok;
> > }
> >
> > static bool
> > @@ -7255,35 +7266,10 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
> > }
> >
> > if (intel_dp->is_mst) {
> > - switch (intel_dp_check_mst_status(intel_dp)) {
> > - case -EINVAL:
> > - /*
> > - * If we were in MST mode, and device is not
> > - * there, get out of MST mode
> > - */
> > - drm_dbg_kms(&i915->drm,
> > - "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);
> > -
> > - return IRQ_NONE;
> > - case 1:
> > - return IRQ_NONE;
> > - default:
> > - break;
> > - }
> > - }
> > -
> > - if (!intel_dp->is_mst) {
> > - bool handled;
> > -
> > - handled = intel_dp_short_pulse(intel_dp);
> > -
> > - if (!handled)
> > + if (!intel_dp_check_mst_status(intel_dp))
> > return IRQ_NONE;
> > + } else if (!intel_dp_short_pulse(intel_dp)) {
> > + return IRQ_NONE;
> > }
> >
>
> Now it don't need the braces but this is minor.
Without the braces it wouldn't be correct.
>
> Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>
> > return IRQ_HANDLED;
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
