From 9137726abc3bc3217dd3adde67c1dce9a1a87c3f Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Thu, 6 Jul 2017 17:40:31 +0300
Subject: [PATCH] drm/i915/gen9+: Remove redundant state check during power well toggling
Git-commit: 9137726abc3bc3217dd3adde67c1dce9a1a87c3f
Patch-mainline: v4.14-rc1
References: FATE#322643 bsc#1055900

Atm we enable/disable a power well only if it wasn't already
enabled/disabled respectively. The only reason for this I can think of
is to save the extra MMIO writes. Since the HW state matches the power
well's usage counter most of the time the overhead due to these MMIOs is
insignificant. Let's simplify the code by making the writes
unconditional.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1499352040-8819-10-git-send-email-imre.deak@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_runtime_pm.c |   25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -806,7 +806,7 @@ static void skl_set_power_well(struct dr
 {
 	uint32_t tmp, fuse_status;
 	uint32_t req_mask, state_mask;
-	bool is_enabled, enable_requested, check_fuse_status = false;
+	bool check_fuse_status = false;
 
 	tmp = I915_READ(HSW_PWR_WELL_DRIVER);
 	fuse_status = I915_READ(SKL_FUSE_STATUS);
@@ -844,29 +844,22 @@ static void skl_set_power_well(struct dr
 	}
 
 	req_mask = SKL_POWER_WELL_REQ(power_well->id);
-	enable_requested = tmp & req_mask;
 	state_mask = SKL_POWER_WELL_STATE(power_well->id);
-	is_enabled = tmp & state_mask;
 
-	if (!enable && enable_requested)
+	if (!enable)
 		skl_power_well_pre_disable(dev_priv, power_well);
 
 	if (enable) {
-		if (!enable_requested)
-			I915_WRITE(HSW_PWR_WELL_DRIVER, tmp | req_mask);
+		I915_WRITE(HSW_PWR_WELL_DRIVER, tmp | req_mask);
 
-		if (!is_enabled) {
-			DRM_DEBUG_KMS("Enabling %s\n", power_well->name);
-			check_fuse_status = true;
-		}
+		DRM_DEBUG_KMS("Enabling %s\n", power_well->name);
+		check_fuse_status = true;
 
 		gen9_wait_for_power_well_enable(dev_priv, power_well);
 	} else {
-		if (enable_requested) {
-			I915_WRITE(HSW_PWR_WELL_DRIVER,	tmp & ~req_mask);
-			POSTING_READ(HSW_PWR_WELL_DRIVER);
-			DRM_DEBUG_KMS("Disabling %s\n", power_well->name);
-		}
+		I915_WRITE(HSW_PWR_WELL_DRIVER,	tmp & ~req_mask);
+		POSTING_READ(HSW_PWR_WELL_DRIVER);
+		DRM_DEBUG_KMS("Disabling %s\n", power_well->name);
 
 		gen9_wait_for_power_well_disable(dev_priv, power_well);
 	}
@@ -889,7 +882,7 @@ static void skl_set_power_well(struct dr
 		}
 	}
 
-	if (enable && !is_enabled)
+	if (enable)
 		skl_power_well_post_enable(dev_priv, power_well);
 }