[PATCH 10/13] drm/i915/dmc_wl: Couple enable/disable with dynamic DC states

[Gustavo Sousa]

Enabling and disabling the DMC wakelock should be done as part of
enabling and disabling of dynamic DC states, respectively. We should not
enable or disable DMC wakelock independently of DC states, otherwise we
would risk ending up with an inconsistent state where dynamic DC states
are enabled and the DMC wakelock is disabled, going against current
recommendations and making MMIO transactions potentially slower. In
future display IPs that could have a worse outcome if DMC trap
implementation is completely removed.

So, let's make things safer by tying stuff together, removing the
independent calls, and also put warnings in place to detect inconsistent
calls.

Signed-off-by: Gustavo Sousa <gustavo.sousa at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_power_well.c | 5 ++++-
 drivers/gpu/drm/i915/display/intel_dmc.c                | 4 ----
 drivers/gpu/drm/i915/display/intel_dmc_wl.c             | 6 ++++--
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.c b/drivers/gpu/drm/i915/display/intel_display_power_well.c
index e8946ce86aaa..1a6c93170a5a 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power_well.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c
@@ -981,6 +981,7 @@ void gen9_disable_dc_states(struct intel_display *display)
 	struct drm_i915_private *dev_priv = to_i915(display->drm);
 	struct i915_power_domains *power_domains = &display->power.domains;
 	struct intel_cdclk_config cdclk_config = {};
+	u32 old_state = power_domains->dc_state;
 
 	if (power_domains->target_dc_state == DC_STATE_EN_DC3CO) {
 		tgl_disable_dc3co(display);
@@ -996,7 +997,9 @@ void gen9_disable_dc_states(struct intel_display *display)
 		return;
 	}
 
-	intel_dmc_wl_disable(display);
+	if (old_state == DC_STATE_EN_UPTO_DC5 ||
+	    old_state == DC_STATE_EN_UPTO_DC6)
+		intel_dmc_wl_disable(display);
 
 	intel_cdclk_get_cdclk(display, &cdclk_config);
 	/* Can't read out voltage_level so can't use intel_cdclk_changed() */
diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
index 48bbbf8f312c..f0b12c609884 100644
--- a/drivers/gpu/drm/i915/display/intel_dmc.c
+++ b/drivers/gpu/drm/i915/display/intel_dmc.c
@@ -632,8 +632,6 @@ void intel_dmc_disable_program(struct intel_display *display)
 	pipedmc_clock_gating_wa(display, true);
 	disable_all_event_handlers(display);
 	pipedmc_clock_gating_wa(display, false);
-
-	intel_dmc_wl_disable(display);
 }
 
 void assert_dmc_loaded(struct intel_display *display)
@@ -1140,8 +1138,6 @@ void intel_dmc_suspend(struct intel_display *display)
 	if (dmc)
 		flush_work(&dmc->work);
 
-	intel_dmc_wl_disable(display);
-
 	/* Drop the reference held in case DMC isn't loaded. */
 	if (!intel_dmc_has_payload(display))
 		intel_dmc_runtime_pm_put(display);
diff --git a/drivers/gpu/drm/i915/display/intel_dmc_wl.c b/drivers/gpu/drm/i915/display/intel_dmc_wl.c
index e27c06b7c42f..8283b607aac4 100644
--- a/drivers/gpu/drm/i915/display/intel_dmc_wl.c
+++ b/drivers/gpu/drm/i915/display/intel_dmc_wl.c
@@ -271,6 +271,7 @@ void intel_dmc_wl_init(struct intel_display *display)
 	refcount_set(&wl->refcount, 0);
 }
 
+/* Must only be called as part of enabling dynamic DC states. */
 void intel_dmc_wl_enable(struct intel_display *display)
 {
 	struct intel_dmc_wl *wl = &display->wl;
@@ -281,7 +282,7 @@ void intel_dmc_wl_enable(struct intel_display *display)
 
 	spin_lock_irqsave(&wl->lock, flags);
 
-	if (wl->enabled)
+	if (drm_WARN_ON(display->drm, wl->enabled))
 		goto out_unlock;
 
 	/*
@@ -314,6 +315,7 @@ void intel_dmc_wl_enable(struct intel_display *display)
 	spin_unlock_irqrestore(&wl->lock, flags);
 }
 
+/* Must only be called as part of disabling dynamic DC states. */
 void intel_dmc_wl_disable(struct intel_display *display)
 {
 	struct intel_dmc_wl *wl = &display->wl;
@@ -326,7 +328,7 @@ void intel_dmc_wl_disable(struct intel_display *display)
 
 	spin_lock_irqsave(&wl->lock, flags);
 
-	if (!wl->enabled)
+	if (drm_WARN_ON(display->drm, !wl->enabled))
 		goto out_unlock;
 
 	/* Disable wakelock in DMC */
-- 
2.47.0