[Intel-gfx] [PATCH 07/11] drm/i915/dp: Exit PSR before do a aux channel transaction

[José Roberto de Souza]

When PSR/PSR2 is enabled hardware can do aux ch transactions by it
self.
Spec requires that PSR is inactive before do any aux ch transaction
in HSW and BDW, for skl+ there is a aux ch mutex but the use is not
recommended.
So exiting PSR/PSR2 and waiting the transition to inactive to prevent
any concurrent access between hardware and software in aux ch
registers.

VLV and CHV hardware don't do any aux as software is responsible to
do all the buffer tracking and it sends the wake up aux ch message
to sink.

BSpec: 7530, 799 and 7532

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h |  2 ++
 drivers/gpu/drm/i915/intel_psr.c |  8 ++++++++
 3 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 62f82c4298ac..fedee4e7ed24 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1062,6 +1062,41 @@ static uint32_t skl_get_aux_send_ctl(struct intel_dp *intel_dp,
 	       DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
 }
 
+/**
+ * intel_dp_aux_ch_get - Get total control of aux ch registers
+ *
+ * By exiting or disabling any hardware feature that can also use the aux ch
+ * registers at the same time as driver, this function will give total control
+ * of aux ch registers to driver.
+ */
+static void intel_dp_aux_ch_get(struct intel_dp *intel_dp)
+{
+	if (!intel_dp->exit_psr_on_aux_ch_xfer)
+		return;
+
+	intel_psr_activate_block_get(intel_dp);
+	intel_psr_exit(intel_dp, true);
+}
+
+/**
+ * intel_dp_aux_ch_put - Release aux ch registers control
+ *
+ * It is the intel_dp_aux_ch_get() counterpart.
+ */
+static void intel_dp_aux_ch_put(struct intel_dp *intel_dp)
+{
+	if (!intel_dp->exit_psr_on_aux_ch_xfer)
+		return;
+
+	intel_psr_activate_block_put(intel_dp);
+	/* Usually more than just one aux ch transaction is executed when
+	 * handling some event, activating PSR right way would cause several
+	 * msecs of delay waiting PSR to exit for each aux ch transaction, so
+	 * here asking it to be scheduled.
+	 */
+	intel_psr_activate(intel_dp, true);
+}
+
 static int
 intel_dp_aux_xfer(struct intel_dp *intel_dp,
 		  const uint8_t *send, int send_bytes,
@@ -1101,6 +1136,8 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 
 	intel_dp_check_edp(intel_dp);
 
+	intel_dp_aux_ch_get(intel_dp);
+
 	/* Try to wait for any previous AUX channel activity */
 	for (try = 0; try < 3; try++) {
 		status = I915_READ_NOTRACE(ch_ctl);
@@ -1223,6 +1260,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 
 	ret = recv_bytes;
 out:
+	intel_dp_aux_ch_put(intel_dp);
 	pm_qos_update_request(&dev_priv->pm_qos, PM_QOS_DEFAULT_VALUE);
 
 	if (vdd)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 020b96324135..177478f0b032 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1139,6 +1139,8 @@ struct intel_dp {
 
 	/* Displayport compliance testing */
 	struct intel_dp_compliance compliance;
+
+	bool exit_psr_on_aux_ch_xfer;
 };
 
 struct intel_lspcon {
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 8702dbafb42d..f88f12246a23 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -665,6 +665,13 @@ void intel_psr_enable(struct intel_dp *intel_dp,
 				      msecs_to_jiffies(intel_dp->panel_power_cycle_delay * 5));
 	}
 
+	/* From all platforms that supports PSR/PSR2 this 2 is the ones that
+	 * don't have restrictions about use of the aux ch while PSR/PSR2 is
+	 * enabled.
+	 */
+	if (!(IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)))
+		intel_dp->exit_psr_on_aux_ch_xfer = true;
+
 unlock:
 	mutex_unlock(&dev_priv->psr.lock);
 }
@@ -732,6 +739,7 @@ void intel_psr_disable(struct intel_dp *intel_dp,
 
 	dev_priv->psr.disable_source(intel_dp);
 
+	intel_dp->exit_psr_on_aux_ch_xfer = false;
 	/* Disable PSR on Sink */
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
 
-- 
2.16.3