[PATCH 5/5] ALSA/i915: Check power well API existense before calling

[Wang Xingchao <xingchao.wang@linux.intel.com>]

I915 module maybe loaded after snd_hda_intel, the power-well
API doesnot exist in such case. This patch intended to avoid
loading dependency between snd-hda-intel and i915 module.

Signed-off-by: Wang Xingchao <xingchao.wang@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_dma.c  |    3 ++
 drivers/gpu/drm/i915/intel_drv.h |    2 ++
 drivers/gpu/drm/i915/intel_pm.c  |   12 +++++++
 include/drm/i915_powerwell.h     |    1 +
 sound/pci/hda/hda_i915.c         |   69 ++++++++++++++++++++++++--------------
 sound/pci/hda/hda_i915.h         |    5 +++
 sound/pci/hda/hda_intel.c        |    8 +++--
 7 files changed, 72 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index a1648eb..307ca4b 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1671,6 +1671,9 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	if (IS_GEN5(dev))
 		intel_gpu_ips_init(dev_priv);
 
+	if (IS_HASWELL(dev))
+		intel_gpu_audio_init();
+
 	return 0;
 
 out_gem_unload:
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index dfcf546..f159f12 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -758,6 +758,8 @@ extern void intel_update_fbc(struct drm_device *dev);
 /* IPS */
 extern void intel_gpu_ips_init(struct drm_i915_private *dev_priv);
 extern void intel_gpu_ips_teardown(void);
+/* Display audio */
+extern void intel_gpu_audio_init(void);
 
 extern bool intel_using_power_well(struct drm_device *dev);
 extern void intel_init_power_well(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 642c4b6..8c1df21 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -29,6 +29,7 @@
 #include "i915_drv.h"
 #include "intel_drv.h"
 #include "../../../platform/x86/intel_ips.h"
+#include "../../../../sound/pci/hda/hda_i915.h"
 #include <linux/module.h>
 
 #define FORCEWAKE_ACK_TIMEOUT_MS 2
@@ -4393,6 +4394,17 @@ struct i915_power_well_user {
 	struct list_head list;
 };
 
+void intel_gpu_audio_init(void)
+{
+	void (*link)(void);
+
+	link = symbol_get(audio_link_to_i915_driver);
+	if (link) {
+		link();
+		symbol_put(audio_link_to_i915_driver);
+	}
+}
+
 void i915_request_power_well(const char *name)
 {
 	struct i915_power_well_user *user;
diff --git a/include/drm/i915_powerwell.h b/include/drm/i915_powerwell.h
index 87e0a2e..de03dc8 100644
--- a/include/drm/i915_powerwell.h
+++ b/include/drm/i915_powerwell.h
@@ -33,6 +33,7 @@
 #ifndef _I915_POWERWELL_H_
 #define _I915_POWERWELL_H_
 
+/* For use by hda_i915 driver */
 extern void i915_request_power_well(const char *name);
 extern void i915_release_power_well(const char *name);
 
diff --git a/sound/pci/hda/hda_i915.c b/sound/pci/hda/hda_i915.c
index edf1a08..d11f255 100644
--- a/sound/pci/hda/hda_i915.c
+++ b/sound/pci/hda/hda_i915.c
@@ -22,54 +22,71 @@
 #include <drm/i915_powerwell.h>
 #include "hda_i915.h"
 
-const char *name = "i915";
-static void (*get_power)(const char *name);
-static void (*put_power)(const char *name);
+char *module_name = "i915";
+void (*get_power)(const char *);
+void (*put_power)(const char *);
+static bool hsw_i915_load;
+
+void audio_link_to_i915_driver(void)
+{
+	/* it's time to try getting the symbols again.*/
+	hsw_i915_load = true;
+}
+EXPORT_SYMBOL_GPL(audio_link_to_i915_driver);
 
 /* Power well has impact on Haswell controller and codecs */
 void hda_display_power(bool enable)
 {
-	snd_printk(KERN_INFO "HDA display power %s \n", enable ? "Enable" : "Disable");
-
-	if (!get_power || !put_power)
-		return;
+	if (!get_power || !put_power) {
+		if (hsw_i915_load) {
+			get_power = i915_request_power_well;
+			put_power = i915_release_power_well;
+		} else
+			return;
+	}
 
+	snd_printk(KERN_DEBUG "HDA display power %s \n",
+			enable ? "Enable" : "Disable");
 	if (enable)
 		get_power("hda");
 	else
 		put_power("hda");
 }
-EXPORT_SYMBOL(hda_display_power);
+EXPORT_SYMBOL_GPL(hda_display_power);
 
-static int __init hda_i915_init(void)
+/* In case i915 module loaded first, the APIs are there.
+ * Otherwise wait until i915 module notify us. */
+int hda_i915_init(void)
 {
-	struct module *i915;
-	mutex_lock(&module_mutex);
-	i915 = find_module(name);
-	mutex_unlock(&module_mutex);
+	struct module *i915;
 
-	if (!i915)
-		request_module_nowait(name);
+	mutex_lock(&module_mutex);
+	i915 = find_module(module_name);
+	mutex_unlock(&module_mutex);
 
-	if (!try_module_get(i915))
-		return -EFAULT;
+	if (!i915)
+		request_module_nowait(module_name);
 
 	get_power = symbol_get(i915_request_power_well);
+	if (!get_power)
+		goto out;
+
 	put_power = symbol_get(i915_release_power_well);
+	if (!put_power)
+		goto out;
 
-	module_put(i915);
+	snd_printk(KERN_DEBUG "HDA driver get symbol successfully from i915 module\n");
+out:
 	return 0;
 }
+EXPORT_SYMBOL_GPL(hda_i915_init);
 
-#if 0
-static void __exit hda_i915_exit(void)
+int hda_i915_exit(void)
 {
-	drm_pci_exit(&driver, &i915_pci_driver);
+	symbol_put(i915_request_power_well);
+	symbol_put(i915_release_power_well);
 }
+EXPORT_SYMBOL_GPL(hda_i915_exit);
 
-module_init(hda_i915_init);
-module_exit(hda_i915_exit);
-#endif
-module_init(hda_i915_init);
-MODULE_DESCRIPTION("HDA power well");
+MODULE_DESCRIPTION("HDA power well For Haswell");
 MODULE_LICENSE("GPL");
diff --git a/sound/pci/hda/hda_i915.h b/sound/pci/hda/hda_i915.h
index a7e5324..b0516ab 100644
--- a/sound/pci/hda/hda_i915.h
+++ b/sound/pci/hda/hda_i915.h
@@ -3,8 +3,13 @@
 
 #ifdef CONFIG_SND_HDA_I915
 void hda_display_power(bool enable);
+int hda_i915_init(void);
+int hda_i915_exit(void);
 #else
 void hda_display_power(bool enable) {}
+int hda_i915_init(void) {}
+int hda_i915_exit(void) {}
 #endif
 
+void audio_link_to_i915_driver(void);
 #endif
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 8bb6075..431027d 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -3684,8 +3684,10 @@ static int azx_probe(struct pci_dev *pci,
 		return -ENOENT;
 	}
 
-	if (IS_HSW(pci))
+	if (IS_HSW(pci)) {
+		hda_i915_init();
 		hda_display_power(true);
+	}
 
 	err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card);
 	if (err < 0) {
@@ -3822,8 +3824,10 @@ static void azx_remove(struct pci_dev *pci)
 	if (card)
 		snd_card_free(card);
 	pci_set_drvdata(pci, NULL);
-	if (IS_HSW(pci))
+	if (IS_HSW(pci)) {
 		hda_display_power(false);
+		hda_i915_exit();
+	}
 }
 
 /* PCI IDs */
-- 
1.7.9.5