drm/i915/gen9: Remove csr.state, csr_lock and related code.

This removes two anti-patterns:
- Locking shouldn't be used to synchronize with async work (of any
  form, whether callbacks, workers or other threads). This is what the
  mutex_lock/unlock seems to have been for in intel_csr_load_program.
  Instead ordering should be ensured with the generic
  wait_for_completion()/complete(). Or more specific functions
  provided by the core kernel like e.g.
  flush_work()/cancel_work_sync() in the case of synchronizing with a
  work item.

- Don't invent own completion like the following code did with the
  (already removed) wait_for(csr_load_status_get()) pattern - it's
  really hard to get these right when you want them to be _really_
  correct (and be fast) in all cases. Furthermore it's easier to read
  code using the well-known primitives than new ones using
  non-standard names.

Before enabling/disabling DC6 check if the firmware is loaded
successfully. This is guaranteed during runtime s/r, since otherwise we
don't enable RPM, but not during system s/r.

Note that it's still unclear whether we need to enable/disable DC6
during system s/r, until that's clarified, keep the current behavior and
enable/disable DC6.

Also after this patch there is a race during system s/r where the
firmware may not be loaded yet, that's addressed in an upcoming patch.

v2-v3:
- unchanged
v4:
- rebased on latest drm-intel-nightly

Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Sunil Kamath <sunil.kamath@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
[imre: added code and note about checking if the firmware loaded ok,
 before enabling/disabling it]
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Tested-by: Daniel Stone <daniels@collabora.com> # SKL
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1447341037-2623-1-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/i915_dma.c

@@ -926,7 +926,6 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	spin_lock_init(&dev_priv->mmio_flip_lock);
 	mutex_init(&dev_priv->sb_lock);
 	mutex_init(&dev_priv->modeset_restore_lock);
-	mutex_init(&dev_priv->csr_lock);
 	mutex_init(&dev_priv->av_mutex);
 
 	intel_pm_setup(dev);

drivers/gpu/drm/i915/i915_drv.c

@@ -1087,18 +1087,11 @@ static int i915_pm_resume(struct device *dev)
 
 static int skl_suspend_complete(struct drm_i915_private *dev_priv)
 {
-	enum csr_state state;
 	/* Enabling DC6 is not a hard requirement to enter runtime D3 */
 
 	skl_uninit_cdclk(dev_priv);
 
-	/* TODO: wait for a completion event or
-	 * similar here instead of busy
-	 * waiting using wait_for function.
-	 */
-	wait_for((state = intel_csr_load_status_get(dev_priv)) !=
-			FW_UNINITIALIZED, 1000);
-	if (state == FW_LOADED)
+	if (dev_priv->csr.dmc_payload)
 		skl_enable_dc6(dev_priv);
 
 	return 0;
@@ -1147,7 +1140,7 @@ static int skl_resume_prepare(struct drm_i915_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
 
-	if (intel_csr_load_status_get(dev_priv) == FW_LOADED)
+	if (dev_priv->csr.dmc_payload)
 		skl_disable_dc6(dev_priv);
 
 	skl_init_cdclk(dev_priv);

drivers/gpu/drm/i915/i915_drv.h

@@ -738,12 +738,6 @@ struct intel_uncore {
 #define CSR_VERSION_MAJOR(version)	((version) >> 16)
 #define CSR_VERSION_MINOR(version)	((version) & 0xffff)
 
-enum csr_state {
-	FW_UNINITIALIZED = 0,
-	FW_LOADED,
-	FW_FAILED
-};
-
 struct intel_csr {
 	const char *fw_path;
 	uint32_t *dmc_payload;
@@ -752,7 +746,6 @@ struct intel_csr {
 	uint32_t mmio_count;
 	uint32_t mmioaddr[8];
 	uint32_t mmiodata[8];
-	enum csr_state state;
 };
 
 #define DEV_INFO_FOR_EACH_FLAG(func, sep) \
@@ -1709,9 +1702,6 @@ struct drm_i915_private {
 
 	struct intel_csr csr;
 
-	/* Display CSR-related protection */
-	struct mutex csr_lock;
-
 	struct intel_gmbus gmbus[GMBUS_NUM_PINS];
 
 	/** gmbus_mutex protects against concurrent usage of the single hw gmbus

drivers/gpu/drm/i915/intel_csr.c

@@ -198,40 +198,6 @@ static const struct stepping_info *intel_get_stepping_info(struct drm_device *de
 	return NULL;
 }
 
-/**
- * intel_csr_load_status_get() - to get firmware loading status.
- * @dev_priv: i915 device.
- *
- * This function helps to get the firmware loading status.
- *
- * Return: Firmware loading status.
- */
-enum csr_state intel_csr_load_status_get(struct drm_i915_private *dev_priv)
-{
-	enum csr_state state;
-
-	mutex_lock(&dev_priv->csr_lock);
-	state = dev_priv->csr.state;
-	mutex_unlock(&dev_priv->csr_lock);
-
-	return state;
-}
-
-/**
- * intel_csr_load_status_set() - help to set firmware loading status.
- * @dev_priv: i915 device.
- * @state: enumeration of firmware loading status.
- *
- * Set the firmware loading status.
- */
-void intel_csr_load_status_set(struct drm_i915_private *dev_priv,
-			enum csr_state state)
-{
-	mutex_lock(&dev_priv->csr_lock);
-	dev_priv->csr.state = state;
-	mutex_unlock(&dev_priv->csr_lock);
-}
-
 /**
  * intel_csr_load_program() - write the firmware from memory to register.
  * @dev: drm device.
@@ -260,7 +226,6 @@ void intel_csr_load_program(struct drm_device *dev)
 	if (I915_READ(CSR_PROGRAM(0)))
 		return;
 
-	mutex_lock(&dev_priv->csr_lock);
 	fw_size = dev_priv->csr.dmc_fw_size;
 	for (i = 0; i < fw_size; i++)
 		I915_WRITE(CSR_PROGRAM(i), payload[i]);
@@ -269,9 +234,6 @@ void intel_csr_load_program(struct drm_device *dev)
 		I915_WRITE(dev_priv->csr.mmioaddr[i],
 			dev_priv->csr.mmiodata[i]);
 	}
-
-	dev_priv->csr.state = FW_LOADED;
-	mutex_unlock(&dev_priv->csr_lock);
 }
 
 static void finish_csr_load(const struct firmware *fw, void *context)
@@ -412,8 +374,6 @@ static void finish_csr_load(const struct firmware *fw, void *context)
 			 CSR_VERSION_MAJOR(csr->version),
 			 CSR_VERSION_MINOR(csr->version));
 	} else {
-		intel_csr_load_status_set(dev_priv, FW_FAILED);
-
 		i915_firmware_load_error_print(csr->fw_path, 0);
 	}
 
@@ -442,7 +402,6 @@ void intel_csr_ucode_init(struct drm_device *dev)
 		csr->fw_path = I915_CSR_BXT;
 	else {
 		DRM_ERROR("Unexpected: no known CSR firmware for platform\n");
-		intel_csr_load_status_set(dev_priv, FW_FAILED);
 		return;
 	}
 
@@ -459,10 +418,8 @@ void intel_csr_ucode_init(struct drm_device *dev)
 				&dev_priv->dev->pdev->dev,
 				GFP_KERNEL, dev_priv,
 				finish_csr_load);
-	if (ret) {
+	if (ret)
 		i915_firmware_load_error_print(csr->fw_path, ret);
-		intel_csr_load_status_set(dev_priv, FW_FAILED);
-	}
 }
 
 /**
@@ -479,6 +436,5 @@ void intel_csr_ucode_fini(struct drm_device *dev)
 	if (!HAS_CSR(dev))
 		return;
 
-	intel_csr_load_status_set(dev_priv, FW_FAILED);
 	kfree(dev_priv->csr.dmc_payload);
 }

drivers/gpu/drm/i915/intel_drv.h

@@ -1221,9 +1221,6 @@ u32 skl_plane_ctl_rotation(unsigned int rotation);
 
 /* intel_csr.c */
 void intel_csr_ucode_init(struct drm_device *dev);
-enum csr_state intel_csr_load_status_get(struct drm_i915_private *dev_priv);
-void intel_csr_load_status_set(struct drm_i915_private *dev_priv,
-					enum csr_state state);
 void intel_csr_load_program(struct drm_device *dev);
 void intel_csr_ucode_fini(struct drm_device *dev);
 

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -663,8 +663,7 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
 	} else {
 		if (enable_requested) {
 			if (IS_SKYLAKE(dev) &&
-				(power_well->data == SKL_DISP_PW_1) &&
-				(intel_csr_load_status_get(dev_priv) == FW_LOADED))
+				(power_well->data == SKL_DISP_PW_1))
 				DRM_DEBUG_KMS("Not Disabling PW1, dmc will handle\n");
 			else {
 				I915_WRITE(HSW_PWR_WELL_DRIVER,	tmp & ~req_mask);
@@ -673,22 +672,10 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
 			}
 
 			if (GEN9_ENABLE_DC5(dev) &&
-				power_well->data == SKL_DISP_PW_2) {
-				enum csr_state state;
-				/* TODO: wait for a completion event or
-				 * similar here instead of busy
-				 * waiting using wait_for function.
-				 */
-				wait_for((state = intel_csr_load_status_get(dev_priv)) !=
-						FW_UNINITIALIZED, 1000);
-				if (state != FW_LOADED)
-					DRM_DEBUG("CSR firmware not ready (%d)\n",
-							state);
-				else
+				power_well->data == SKL_DISP_PW_2)
 					gen9_enable_dc5(dev_priv);
 		}
 	}
-	}
 
 	if (check_fuse_status) {
 		if (power_well->data == SKL_DISP_PW_1) {