drm/i915: Use RPM as the barrier for controlling user mmap access

We can remove the false coupling between RPM and struct mutex by the
observation that we can use the RPM wakeref as the barrier around user
mmap access. That is as we tear down the user's PTE atomically from
within rpm suspend and then to fault in new PTE requires the rpm
wakeref, means that no user access is possible through those PTE without
RPM being awake. Having made that observation, we can then remove the
presumption of having to take rpm outside of struct_mutex and so allow
fine grained acquisition of a wakeref around hw access rather than
having to remember to acquire the wakeref early on.

v2: Rejig placement of the new intel_runtime_pm_get() to be as tight
as possible around the GTT pread/pwrite.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161024124218.18252-2-chris@chris-wilson.co.uk

1 files changed, 33 insertions, 23 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 2d9617a3472d..f85e6fbf27f4 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -743,17 +743,32 @@ static int i915_interrupt_info(struct seq_file *m, void *data)
 			   I915_READ(VLV_IIR_RW));
 		seq_printf(m, "Display IMR:\t%08x\n",
 			   I915_READ(VLV_IMR));
-		for_each_pipe(dev_priv, pipe)
+		for_each_pipe(dev_priv, pipe) {
+			enum intel_display_power_domain power_domain;
+
+			power_domain = POWER_DOMAIN_PIPE(pipe);
+			if (!intel_display_power_get_if_enabled(dev_priv,
+								power_domain)) {
+				seq_printf(m, "Pipe %c power disabled\n",
+					   pipe_name(pipe));
+				continue;
+			}
+
 			seq_printf(m, "Pipe %c stat:\t%08x\n",
 				   pipe_name(pipe),
 				   I915_READ(PIPESTAT(pipe)));
 
+			intel_display_power_put(dev_priv, power_domain);
+		}
+
+		intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
 		seq_printf(m, "Port hotplug:\t%08x\n",
 			   I915_READ(PORT_HOTPLUG_EN));
 		seq_printf(m, "DPFLIPSTAT:\t%08x\n",
 			   I915_READ(VLV_DPFLIPSTAT));
 		seq_printf(m, "DPINVGTT:\t%08x\n",
 			   I915_READ(DPINVGTT));
+		intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
 
 		for (i = 0; i < 4; i++) {
 			seq_printf(m, "GT Interrupt IMR %d:\t%08x\n",
@@ -1396,14 +1411,9 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 static int ironlake_drpc_info(struct seq_file *m)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
-	struct drm_device *dev = &dev_priv->drm;
 	u32 rgvmodectl, rstdbyctl;
 	u16 crstandvid;
-	int ret;
 
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
 	intel_runtime_pm_get(dev_priv);
 
 	rgvmodectl = I915_READ(MEMMODECTL);
@@ -1411,7 +1421,6 @@ static int ironlake_drpc_info(struct seq_file *m)
 	crstandvid = I915_READ16(CRSTANDVID);
 
 	intel_runtime_pm_put(dev_priv);
-	mutex_unlock(&dev->struct_mutex);
 
 	seq_printf(m, "HD boost: %s\n", yesno(rgvmodectl & MEMMODE_BOOST_EN));
 	seq_printf(m, "Boost freq: %d\n",
@@ -1757,6 +1766,7 @@ static int i915_sr_status(struct seq_file *m, void *unused)
 	bool sr_enabled = false;
 
 	intel_runtime_pm_get(dev_priv);
+	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
 
 	if (HAS_PCH_SPLIT(dev_priv))
 		sr_enabled = I915_READ(WM1_LP_ILK) & WM1_LP_SR_EN;
@@ -1770,6 +1780,7 @@ static int i915_sr_status(struct seq_file *m, void *unused)
 	else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		sr_enabled = I915_READ(FW_BLC_SELF_VLV) & FW_CSPWRDWNEN;
 
+	intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
 	intel_runtime_pm_put(dev_priv);
 
 	seq_printf(m, "self-refresh: %s\n",
@@ -2091,12 +2102,7 @@ static const char *swizzle_string(unsigned swizzle)
 static int i915_swizzle_info(struct seq_file *m, void *data)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
-	struct drm_device *dev = &dev_priv->drm;
-	int ret;
 
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
 	intel_runtime_pm_get(dev_priv);
 
 	seq_printf(m, "bit6 swizzle for X-tiling = %s\n",
@@ -2136,7 +2142,6 @@ static int i915_swizzle_info(struct seq_file *m, void *data)
 		seq_puts(m, "L-shaped memory detected\n");
 
 	intel_runtime_pm_put(dev_priv);
-	mutex_unlock(&dev->struct_mutex);
 
 	return 0;
 }
@@ -2542,11 +2547,22 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
 		enabled = I915_READ(EDP_PSR_CTL) & EDP_PSR_ENABLE;
 	else {
 		for_each_pipe(dev_priv, pipe) {
+			enum transcoder cpu_transcoder =
+				intel_pipe_to_cpu_transcoder(dev_priv, pipe);
+			enum intel_display_power_domain power_domain;
+
+			power_domain = POWER_DOMAIN_TRANSCODER(cpu_transcoder);
+			if (!intel_display_power_get_if_enabled(dev_priv,
+								power_domain))
+				continue;
+
 			stat[pipe] = I915_READ(VLV_PSRSTAT(pipe)) &
 				VLV_EDP_PSR_CURR_STATE_MASK;
 			if ((stat[pipe] == VLV_EDP_PSR_ACTIVE_NORFB_UP) ||
 			    (stat[pipe] == VLV_EDP_PSR_ACTIVE_SF_UPDATE))
 				enabled = true;
+
+			intel_display_power_put(dev_priv, power_domain);
 		}
 	}
 
@@ -3094,6 +3110,8 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 
+	intel_runtime_pm_get(dev_priv);
+
 	for_each_engine(engine, dev_priv, id) {
 		struct intel_breadcrumbs *b = &engine->breadcrumbs;
 		struct drm_i915_gem_request *rq;
@@ -3213,6 +3231,8 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 		seq_puts(m, "\n");
 	}
 
+	intel_runtime_pm_put(dev_priv);
+
 	return 0;
 }
 
@@ -4799,13 +4819,9 @@ i915_wedged_set(void *data, u64 val)
 	if (i915_reset_in_progress(&dev_priv->gpu_error))
 		return -EAGAIN;
 
-	intel_runtime_pm_get(dev_priv);
-
 	i915_handle_error(dev_priv, val,
 			  "Manually setting wedged to %llu", val);
 
-	intel_runtime_pm_put(dev_priv);
-
 	return 0;
 }
 
@@ -5040,22 +5056,16 @@ static int
 i915_cache_sharing_get(void *data, u64 *val)
 {
 	struct drm_i915_private *dev_priv = data;
-	struct drm_device *dev = &dev_priv->drm;
 	u32 snpcr;
-	int ret;
 
 	if (!(IS_GEN6(dev_priv) || IS_GEN7(dev_priv)))
 		return -ENODEV;
 
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
 	intel_runtime_pm_get(dev_priv);
 
 	snpcr = I915_READ(GEN6_MBCUNIT_SNPCR);
 
 	intel_runtime_pm_put(dev_priv);
-	mutex_unlock(&dev->struct_mutex);
 
 	*val = (snpcr & GEN6_MBC_SNPCR_MASK) >> GEN6_MBC_SNPCR_SHIFT;