[PATCH] drm/i915/psr: Clean-up intel_enable_source_psr1()

[Jim Bride <jim.bride@linux.intel.com>]

On SKL+ there is a bit in SRD_CTL that software is not supposed to
modify, but we currently clobber that bit when we enable PSR.  In
order to preserve the value of that bit, go ahead and read SRD_CTL and
do a field-wise setting of the various bits that we need to initialize
before writing the register back out.  Additionally, go ahead and
explicitly disable single-frame update since we aren't currently
supporting it.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Wayne Boyer <wayne.boyer@intel.com>

Signed-off-by: Jim Bride <jim.bride@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  3 +++
 drivers/gpu/drm/i915/intel_psr.c | 23 +++++++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 11b12f4..54d39e4 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3590,14 +3590,17 @@ enum {
 #define   EDP_PSR_SKIP_AUX_EXIT			(1<<12)
 #define   EDP_PSR_TP1_TP2_SEL			(0<<11)
 #define   EDP_PSR_TP1_TP3_SEL			(1<<11)
+#define   EDP_PSR_TP2_TP3_TIME_MASK             (3<<8)
 #define   EDP_PSR_TP2_TP3_TIME_500us		(0<<8)
 #define   EDP_PSR_TP2_TP3_TIME_100us		(1<<8)
 #define   EDP_PSR_TP2_TP3_TIME_2500us		(2<<8)
 #define   EDP_PSR_TP2_TP3_TIME_0us		(3<<8)
+#define   EDP_PSR_TP1_TIME_MASK                 (0x3<<4)
 #define   EDP_PSR_TP1_TIME_500us		(0<<4)
 #define   EDP_PSR_TP1_TIME_100us		(1<<4)
 #define   EDP_PSR_TP1_TIME_2500us		(2<<4)
 #define   EDP_PSR_TP1_TIME_0us			(3<<4)
+#define   EDP_PSR_IDLE_FRAME_MASK               (0xf<<0)
 #define   EDP_PSR_IDLE_FRAME_SHIFT		0
 
 #define EDP_PSR_AUX_CTL				_MMIO(dev_priv->psr_mmio_base + 0x10)
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index c3780d0..a050859 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -280,17 +280,34 @@ static void intel_enable_source_psr1(struct intel_dp *intel_dp)
 	 * with the 5 or 6 idle patterns.
 	 */
 	uint32_t idle_frames = max(6, dev_priv->vbt.psr.idle_frames);
-	uint32_t val = EDP_PSR_ENABLE;
+	uint32_t val = I915_READ(EDP_PSR_CTL);
 
+	val |= EDP_PSR_ENABLE;
+
+	/* We always set the max sleep time to the maximum value, so
+	 * no need to zero out the field first.
+	 */
 	val |= max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT;
+
+	val &= ~EDP_PSR_IDLE_FRAME_MASK;
 	val |= idle_frames << EDP_PSR_IDLE_FRAME_SHIFT;
 
+	val &= ~EDP_PSR_MIN_LINK_ENTRY_TIME_MASK;
 	if (IS_HASWELL(dev_priv))
 		val |= EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
 
-	if (dev_priv->psr.link_standby)
+	if (dev_priv->psr.link_standby) {
 		val |= EDP_PSR_LINK_STANDBY;
 
+		/* SFU should only be enabled with link standby, but for
+		 * now we do not support it. */
+		val &= ~BDW_PSR_SINGLE_FRAME;
+	} else {
+		val &= ~EDP_PSR_LINK_STANDBY;
+		val &= ~BDW_PSR_SINGLE_FRAME;
+	}
+
+	val &= ~EDP_PSR_TP1_TIME_MASK;
 	if (dev_priv->vbt.psr.tp1_wakeup_time > 5)
 		val |= EDP_PSR_TP1_TIME_2500us;
 	else if (dev_priv->vbt.psr.tp1_wakeup_time > 1)
@@ -300,6 +317,7 @@ static void intel_enable_source_psr1(struct intel_dp *intel_dp)
 	else
 		val |= EDP_PSR_TP1_TIME_0us;
 
+	val &= ~EDP_PSR_TP2_TP3_TIME_MASK;
 	if (dev_priv->vbt.psr.tp2_tp3_wakeup_time > 5)
 		val |= EDP_PSR_TP2_TP3_TIME_2500us;
 	else if (dev_priv->vbt.psr.tp2_tp3_wakeup_time > 1)
@@ -309,6 +327,7 @@ static void intel_enable_source_psr1(struct intel_dp *intel_dp)
 	else
 		val |= EDP_PSR_TP2_TP3_TIME_0us;
 
+	val &= ~EDP_PSR_TP1_TP3_SEL;
 	if (intel_dp_source_supports_hbr2(intel_dp) &&
 	    drm_dp_tps3_supported(intel_dp->dpcd))
 		val |= EDP_PSR_TP1_TP3_SEL;
-- 
2.7.4

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