[PATCH 4/4] drm/i915: Check PSR errors instead of retrain while PSR is enabled

["José Roberto de Souza" <jose.souza@intel.com>]

When a PSR error happens sink also update the link status values
while source do not retrain link as required in the PSR exit
sequence.
So in the short pulse handling it was returning earlier and doing a
full detection and attempting to retrain but it fails because for
most sinks the main link is disabled while PSR is active, before even
check PSR errors.

Just call intel_psr_short_pulse() before
intel_dp_needs_link_retrain() is also not the right fix as
intel_dp_needs_link_retrain() would return true and trigger a full
detection and trying to retrain link while PSR HW is also doing that.

Check for PSR active is also not safe as it could be inactive due a
frontbuffer invalidate and still doing the PSR exit sequence.

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  |  7 +++++++
 drivers/gpu/drm/i915/intel_drv.h |  1 +
 drivers/gpu/drm/i915/intel_psr.c | 15 +++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 4a1c31ec9065..f89802bdf525 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4363,6 +4363,13 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
 	if (!intel_dp->link_trained)
 		return false;
 
+	/*
+	 * While PSR is enabled, HW will control main-link and retrain when
+	 * exiting PSR
+	 */
+	if (intel_psr_enabled(intel_dp))
+		return false;
+
 	if (!intel_dp_get_link_status(intel_dp, link_status))
 		return false;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 43190c6e9ef2..e2076ec9d965 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1958,6 +1958,7 @@ void intel_psr_irq_handler(struct drm_i915_private *dev_priv, u32 psr_iir);
 void intel_psr_short_pulse(struct intel_dp *intel_dp);
 int intel_psr_wait_for_idle(const struct intel_crtc_state *new_crtc_state,
 			    u32 *out_value);
+bool intel_psr_enabled(struct intel_dp *intel_dp);
 
 /* intel_runtime_pm.c */
 int intel_power_domains_init(struct drm_i915_private *);
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 74090fffea23..63c00c802fa7 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -1155,3 +1155,18 @@ void intel_psr_short_pulse(struct intel_dp *intel_dp)
 exit:
 	mutex_unlock(&psr->lock);
 }
+
+bool intel_psr_enabled(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	bool ret;
+
+	if (!CAN_PSR(dev_priv) || !intel_dp_is_edp(intel_dp))
+		return false;
+
+	mutex_lock(&dev_priv->psr.lock);
+	ret = (dev_priv->psr.dp == intel_dp && dev_priv->psr.enabled);
+	mutex_unlock(&dev_priv->psr.lock);
+
+	return ret;
+}
-- 
2.19.0

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