[alsa-devel] [PATCH] drm/i915, HD-audio: Don't continue probing when nomodeset is given

[Takashi Iwai]

When a machine is booted with nomodeset option, i915 driver skips the
whole initialization.  Meanwhile, HD-audio tries to bind wth i915 just
by request_symbol() without knowing that the initialization was
skipped, and eventually it hits WARN_ON() in i915_request_power_well()
and i915_release_power_well() wrongly but still continues probing,
even though it doesn't work at all.

In this patch, both functions are changed to return an error in case
of uninitialized state instead of WARN_ON(), so that HD-audio driver
can give up HDMI controller initialization at the right time.

Cc: <stable at vger.kernel.org> [3.15]
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---

The bug actually exists since 3.11, but this commit will be applicable
only to recent kernels due to ALSA and i915 code changes, that's why
marked with [3.15] for stable.

 drivers/gpu/drm/i915/intel_pm.c | 14 ++++++++------
 include/drm/i915_powerwell.h    |  4 ++--
 sound/pci/hda/hda_i915.c        | 12 ++++++------
 sound/pci/hda/hda_i915.h        |  4 ++--
 sound/pci/hda/hda_intel.c       |  7 ++++++-
 5 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d93dcf683e8c..0d6bd247009b 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5706,30 +5706,32 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 static struct i915_power_domains *hsw_pwr;
 
 /* Display audio driver power well request */
-void i915_request_power_well(void)
+int i915_request_power_well(void)
 {
 	struct drm_i915_private *dev_priv;
 
-	if (WARN_ON(!hsw_pwr))
-		return;
+	if (!hsw_pwr)
+		return -ENODEV;
 
 	dev_priv = container_of(hsw_pwr, struct drm_i915_private,
 				power_domains);
 	intel_display_power_get(dev_priv, POWER_DOMAIN_AUDIO);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(i915_request_power_well);
 
 /* Display audio driver power well release */
-void i915_release_power_well(void)
+int i915_release_power_well(void)
 {
 	struct drm_i915_private *dev_priv;
 
-	if (WARN_ON(!hsw_pwr))
-		return;
+	if (!hsw_pwr)
+		return -ENODEV;
 
 	dev_priv = container_of(hsw_pwr, struct drm_i915_private,
 				power_domains);
 	intel_display_power_put(dev_priv, POWER_DOMAIN_AUDIO);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(i915_release_power_well);
 
diff --git a/include/drm/i915_powerwell.h b/include/drm/i915_powerwell.h
index cfdc884405b7..2baba9996094 100644
--- a/include/drm/i915_powerwell.h
+++ b/include/drm/i915_powerwell.h
@@ -30,7 +30,7 @@
 #define _I915_POWERWELL_H_
 
 /* For use by hda_i915 driver */
-extern void i915_request_power_well(void);
-extern void i915_release_power_well(void);
+extern int i915_request_power_well(void);
+extern int i915_release_power_well(void);
 
 #endif				/* _I915_POWERWELL_H_ */
diff --git a/sound/pci/hda/hda_i915.c b/sound/pci/hda/hda_i915.c
index 9d07e4edacdb..e9e8a4a4a9a1 100644
--- a/sound/pci/hda/hda_i915.c
+++ b/sound/pci/hda/hda_i915.c
@@ -22,20 +22,20 @@
 #include <drm/i915_powerwell.h>
 #include "hda_i915.h"
 
-static void (*get_power)(void);
-static void (*put_power)(void);
+static int (*get_power)(void);
+static int (*put_power)(void);
 
-void hda_display_power(bool enable)
+int hda_display_power(bool enable)
 {
 	if (!get_power || !put_power)
-		return;
+		return -ENODEV;
 
 	pr_debug("HDA display power %s \n",
 			enable ? "Enable" : "Disable");
 	if (enable)
-		get_power();
+		return get_power();
 	else
-		put_power();
+		return put_power();
 }
 
 int hda_i915_init(void)
diff --git a/sound/pci/hda/hda_i915.h b/sound/pci/hda/hda_i915.h
index 5a63da2c53e5..bfd835f8f1aa 100644
--- a/sound/pci/hda/hda_i915.h
+++ b/sound/pci/hda/hda_i915.h
@@ -17,11 +17,11 @@
 #define __SOUND_HDA_I915_H
 
 #ifdef CONFIG_SND_HDA_I915
-void hda_display_power(bool enable);
+int hda_display_power(bool enable);
 int hda_i915_init(void);
 int hda_i915_exit(void);
 #else
-static inline void hda_display_power(bool enable) {}
+static inline int hda_display_power(bool enable) { return 0; }
 static inline int hda_i915_init(void)
 {
 	return -ENODEV;
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index bb65a124e006..23fd6b9aecca 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1656,8 +1656,13 @@ static int azx_probe_continue(struct azx *chip)
 				"Error request power-well from i915\n");
 			goto out_free;
 		}
+		err = hda_display_power(true);
+		if (err < 0) {
+			dev_err(chip->card->dev,
+				"Cannot turn on display power on i915\n");
+			goto out_free;
+		}
 #endif
-		hda_display_power(true);
 	}
 
 	err = azx_first_init(chip);
-- 
1.9.3