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| author | Takashi Iwai <tiwai@suse.de> | 2016-03-04 11:34:18 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-12 07:33:31 -0700 |
| commit | cf5c079c8112aa87b7c724f91ce878cb127c0848 (patch) | |
| tree | 5a12379295abae74080e12a508f859f954fc4df6 /include | |
| parent | 840c32e2275c9e7dd6eb50b0cb13a80a4c64149e (diff) | |
| download | lwn-cf5c079c8112aa87b7c724f91ce878cb127c0848.tar.gz lwn-cf5c079c8112aa87b7c724f91ce878cb127c0848.zip | |
ALSA: hda - Fix unexpected resume through regmap code path
commit fc4f000bf8c0cbf38f44de6bd5e225574e572ed4 upstream.
HD-audio driver has a mechanism to trigger the runtime resume
automatically at accessing the verbs. This auto-resume, however,
causes the mutex deadlock when invoked from the regmap handler since
the regmap keeps the mutex while auto-resuming. For avoiding that,
there is some tricky check in the HDA regmap handler to return -EAGAIN
error to back-off when the codec is powered down. Then the caller of
regmap r/w will retry after properly turning on the codec power.
This works in most cases, but there seems a slight race between the
codec power check and the actual on-demand auto-resume trigger. This
resulted in the lockdep splat, eventually leading to a real deadlock.
This patch tries to address the race window by getting the runtime PM
refcount at the check time using pm_runtime_get_if_in_use(). With
this call, we can keep the power on only when the codec has been
already turned on, and back off if not.
For keeping the code consistency, the code touching the runtime PM is
stored in hdac_device.c although it's used only locally in
hdac_regmap.c.
Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/sound/hdaudio.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h index c21c38ce7450..93e63c56f48f 100644 --- a/include/sound/hdaudio.h +++ b/include/sound/hdaudio.h @@ -168,11 +168,13 @@ int snd_hdac_power_up(struct hdac_device *codec); int snd_hdac_power_down(struct hdac_device *codec); int snd_hdac_power_up_pm(struct hdac_device *codec); int snd_hdac_power_down_pm(struct hdac_device *codec); +int snd_hdac_keep_power_up(struct hdac_device *codec); #else static inline int snd_hdac_power_up(struct hdac_device *codec) { return 0; } static inline int snd_hdac_power_down(struct hdac_device *codec) { return 0; } static inline int snd_hdac_power_up_pm(struct hdac_device *codec) { return 0; } static inline int snd_hdac_power_down_pm(struct hdac_device *codec) { return 0; } +static inline int snd_hdac_keep_power_up(struct hdac_device *codec) { return 0; } #endif /* |