linux/sound/pci/hda/hda_i915.c
Wang Xingchao 99a2008d0b 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 <xingchao.wang@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2013-06-06 17:31:56 +02:00

76 lines
1.8 KiB
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;
}