ALSA: hda - Add power-welll support for haswell HDA

For Intel Haswell chip, HDA controller and codec have
power well dependency from GPU side. This patch added support
to request/release power well in audio driver. Power save
feature should be enabled to get runtime power saving.

There's deadlock when request_module(i915) in azx_probe.
It looks like:
device_lock(audio pci device) -> azx_probe -> module_request
(or symbol_request) -> modprobe (userspace) -> i915 init ->
drm_pci_init -> pci_register_driver -> bus_add_driver -> driver_attach ->
which in turn tries all locks on pci bus, and when it tries the one on the
audio device, it will deadlock.

This patch introduce a work to store remaining probe stuff, and let
request_module run in safe work context.

Signed-off-by: Wang Xingchao <[e-mail]>
Reviewed-by: Takashi Iwai <[e-mail]>
Reviewed-by: Liam Girdwood <[e-mail]>
Reviewed-by: David Henningsson <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

sound/pci/hda/Kconfig

···
 	  snd-hda-codec-hdmi.
 	  This module is automatically loaded at probing.
 
+config SND_HDA_I915
+	bool "Build Display HD-audio controller/codec power well support for i915 cards"
+	depends on DRM_I915
+	help
+	  Say Y here to include full HDMI and DisplayPort HD-audio controller/codec
+	  power-well support for Intel Haswell graphics cards based on the i915 driver.
+
+	  Note that this option must be enabled for Intel Haswell C+ stepping machines, otherwise
+	  the GPU audio controller/codecs will not be initialized or damaged when exit from S3 mode.
+
 config SND_HDA_CODEC_CIRRUS
 	bool "Build Cirrus Logic codec support"
 	default y

sound/pci/hda/Makefile

···
 snd-hda-intel-objs := hda_intel.o
+# for haswell power well
+snd-hda-intel-$(CONFIG_SND_HDA_I915) +=	hda_i915.o
 
 snd-hda-codec-y := hda_codec.o hda_jack.o hda_auto_parser.o
 snd-hda-codec-$(CONFIG_SND_HDA_GENERIC) += hda_generic.o

sound/pci/hda/hda_i915.c

···
+/*
+ *  hda_i915.c - routines for Haswell HDA controller power well support
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation; either version 2 of the License, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ *  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software Foundation,
+ *  Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <drm/i915_powerwell.h>
+#include "hda_i915.h"
+
+static void (*get_power)(void);
+static void (*put_power)(void);
+
+void hda_display_power(bool enable)
+{
+	if (!get_power || !put_power)
+		return;
+
+	snd_printdd("HDA display power %s \n",
+			enable ? "Enable" : "Disable");
+	if (enable)
+		get_power();
+	else
+		put_power();
+}
+
+int hda_i915_init(void)
+{
+	int err = 0;
+
+	get_power = symbol_request(i915_request_power_well);
+	if (!get_power) {
+		snd_printk(KERN_WARNING "hda-i915: get_power symbol get fail\n");
+		return -ENODEV;
+	}
+
+	put_power = symbol_request(i915_release_power_well);
+	if (!put_power) {
+		symbol_put(i915_request_power_well);
+		get_power = NULL;
+		return -ENODEV;
+	}
+
+	snd_printd("HDA driver get symbol successfully from i915 module\n");
+
+	return err;
+}
+
+int hda_i915_exit(void)
+{
+	if (get_power) {
+		symbol_put(i915_request_power_well);
+		get_power = NULL;
+	}
+	if (put_power) {
+		symbol_put(i915_release_power_well);
+		put_power = NULL;
+	}
+
+	return 0;
+}

sound/pci/hda/hda_i915.h

···
+/*
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation; either version 2 of the License, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ *  more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program; if not, write to the Free Software Foundation, Inc., 59
+ *  Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+#ifndef __SOUND_HDA_I915_H
+#define __SOUND_HDA_I915_H
+
+#ifdef CONFIG_SND_HDA_I915
+void 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_i915_init(void)
+{
+	return -ENODEV;
+}
+static inline int hda_i915_exit(void)
+{
+	return 0;
+}
+#endif
+
+#endif

sound/pci/hda/hda_intel.c

···
 #include <linux/vga_switcheroo.h>
 #include <linux/firmware.h>
 #include "hda_codec.h"
+#include "hda_i915.h"
 
 
 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
···
 	/* for pending irqs */
 	struct work_struct irq_pending_work;
 
+#ifdef CONFIG_SND_HDA_I915
+	struct work_struct probe_work;
+#endif
+
 	/* reboot notifier (for mysterious hangup problem at power-down) */
 	struct notifier_block reboot_notifier;
 
···
 #define AZX_DCAPS_4K_BDLE_BOUNDARY (1 << 23)	/* BDLE in 4k boundary */
 #define AZX_DCAPS_COUNT_LPIB_DELAY  (1 << 25)	/* Take LPIB as delay */
 #define AZX_DCAPS_PM_RUNTIME	(1 << 26)	/* runtime PM support */
+#define AZX_DCAPS_I915_POWERWELL (1 << 27)	/* HSW i915 power well support */
 
 /* quirks for Intel PCH */
 #define AZX_DCAPS_INTEL_PCH_NOPM \
···
 	pci_disable_device(pci);
 	pci_save_state(pci);
 	pci_set_power_state(pci, PCI_D3hot);
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
+		hda_display_power(false);
 	return 0;
 }
 
···
 	if (chip->disabled)
 		return 0;
 
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
+		hda_display_power(true);
 	pci_set_power_state(pci, PCI_D0);
 	pci_restore_state(pci);
 	if (pci_enable_device(pci) < 0) {
···
 
 	azx_stop_chip(chip);
 	azx_clear_irq_pending(chip);
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
+		hda_display_power(false);
 	return 0;
 }
 
···
 	struct snd_card *card = dev_get_drvdata(dev);
 	struct azx *chip = card->private_data;
 
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
+		hda_display_power(true);
 	azx_init_pci(chip);
 	azx_init_chip(chip, 1);
 	return 0;
···
 	if (chip->fw)
 		release_firmware(chip->fw);
 #endif
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL) {
+		hda_display_power(false);
+		hda_i915_exit();
+	}
 	kfree(chip);
 
 	return 0;
···
 	}
 }
 
+#ifdef CONFIG_SND_HDA_I915
+static void azx_probe_work(struct work_struct *work)
+{
+	azx_probe_continue(container_of(work, struct azx, probe_work));
+}
+#endif
+
 /*
  * constructor
  */
···
 		return err;
 	}
 
+#ifdef CONFIG_SND_HDA_I915
+	/* continue probing in work context as may trigger request module */
+	INIT_WORK(&chip->probe_work, azx_probe_work);
+#endif
+
 	*rchip = chip;
+
 	return 0;
 }
 
···
 	}
 #endif /* CONFIG_SND_HDA_PATCH_LOADER */
 
+	/* continue probing in work context, avoid request_module deadlock */
+	if (probe_now && (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)) {
+#ifdef CONFIG_SND_HDA_I915
+		probe_now = false;
+		schedule_work(&chip->probe_work);
+#else
+		snd_printk(KERN_ERR SFX "Haswell must build in CONFIG_SND_HDA_I915\n");
+#endif
+	}
+
 	if (probe_now) {
 		err = azx_probe_continue(chip);
 		if (err < 0)
···
 	struct pci_dev *pci = chip->pci;
 	int dev = chip->dev_index;
 	int err;
+
+	/* Request power well for Haswell HDA controller and codec */
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL) {
+		err = hda_i915_init();
+		if (err < 0) {
+			snd_printk(KERN_ERR SFX "Error request power-well from i915\n");
+			goto out_free;
+		}
+		hda_display_power(true);
+	}
 
 	err = azx_first_init(chip);
 	if (err < 0)
···
 	  .driver_data = AZX_DRIVER_PCH | AZX_DCAPS_INTEL_PCH },
 	/* Haswell */
 	{ PCI_DEVICE(0x8086, 0x0a0c),
-	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH },
+	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH |
+	  AZX_DCAPS_I915_POWERWELL },
 	{ PCI_DEVICE(0x8086, 0x0c0c),
-	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH },
+	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH |
+	  AZX_DCAPS_I915_POWERWELL },
 	{ PCI_DEVICE(0x8086, 0x0d0c),
-	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH },
+	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH |
+	  AZX_DCAPS_I915_POWERWELL },
 	/* 5 Series/3400 */
 	{ PCI_DEVICE(0x8086, 0x3b56),
 	  .driver_data = AZX_DRIVER_SCH | AZX_DCAPS_INTEL_PCH_NOPM },