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linux/include/sound/hda_regmap.h
Takashi Iwai 3194ed4979 ALSA: hda - Fix possible race on regmap bypass flip 
HD-audio driver uses regmap cache bypass feature for reading a raw
value without the cache.  But this is racy since both the cached and
the uncached reads may occur concurrently.  The former is done via the
normal control API access while the latter comes from the proc file
read.

Even though the regmap itself has the protection against the
concurrent accesses, the flag set/reset is done without the
protection, so it may lead to inconsistent state of bypass flag that
doesn't match with the current read and occasionally result in a
kernel WARNING like:
  WARNING: CPU: 3 PID: 2731 at drivers/base/regmap/regcache.c:499 regcache_cache_only+0x78/0x93

One way to work around such a problem is to wrap with a mutex.  But in
this case, the solution is simpler: for the uncached read, we just
skip the regmap and directly calls its accessor.  The verb execution
there is protected by itself, so basically it's safe to call
individually.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=116171
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-04-21 17:59:17 +02:00

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/*
* HD-audio regmap helpers
*/
#ifndef __SOUND_HDA_REGMAP_H
#define __SOUND_HDA_REGMAP_H
#include <linux/regmap.h>
#include <sound/core.h>
#include <sound/hdaudio.h>
#define AC_AMP_FAKE_MUTE 0x10 /* fake mute bit set to amp verbs */
int snd_hdac_regmap_init(struct hdac_device *codec);
void snd_hdac_regmap_exit(struct hdac_device *codec);
int snd_hdac_regmap_add_vendor_verb(struct hdac_device *codec,
unsigned int verb);
int snd_hdac_regmap_read_raw(struct hdac_device *codec, unsigned int reg,
unsigned int *val);
int snd_hdac_regmap_read_raw_uncached(struct hdac_device *codec,
unsigned int reg, unsigned int *val);
int snd_hdac_regmap_write_raw(struct hdac_device *codec, unsigned int reg,
unsigned int val);
int snd_hdac_regmap_update_raw(struct hdac_device *codec, unsigned int reg,
unsigned int mask, unsigned int val);
/**
* snd_hdac_regmap_encode_verb - encode the verb to a pseudo register
* @nid: widget NID
* @verb: codec verb
*
* Returns an encoded pseudo register.
*/
#define snd_hdac_regmap_encode_verb(nid, verb) \
(((verb) << 8) | 0x80000 | ((unsigned int)(nid) << 20))
/**
* snd_hdac_regmap_encode_amp - encode the AMP verb to a pseudo register
* @nid: widget NID
* @ch: channel (left = 0, right = 1)
* @dir: direction (#HDA_INPUT, #HDA_OUTPUT)
* @idx: input index value
*
* Returns an encoded pseudo register.
*/
#define snd_hdac_regmap_encode_amp(nid, ch, dir, idx) \
(snd_hdac_regmap_encode_verb(nid, AC_VERB_GET_AMP_GAIN_MUTE) | \
((ch) ? AC_AMP_GET_RIGHT : AC_AMP_GET_LEFT) | \
((dir) == HDA_OUTPUT ? AC_AMP_GET_OUTPUT : AC_AMP_GET_INPUT) | \
(idx))
/**
* snd_hdac_regmap_encode_amp_stereo - encode a pseudo register for stereo AMPs
* @nid: widget NID
* @dir: direction (#HDA_INPUT, #HDA_OUTPUT)
* @idx: input index value
*
* Returns an encoded pseudo register.
*/
#define snd_hdac_regmap_encode_amp_stereo(nid, dir, idx) \
(snd_hdac_regmap_encode_verb(nid, AC_VERB_GET_AMP_GAIN_MUTE) | \
AC_AMP_SET_LEFT | AC_AMP_SET_RIGHT | /* both bits set! */ \
((dir) == HDA_OUTPUT ? AC_AMP_GET_OUTPUT : AC_AMP_GET_INPUT) | \
(idx))
/**
* snd_hdac_regmap_write - Write a verb with caching
* @nid: codec NID
* @reg: verb to write
* @val: value to write
*
* For writing an amp value, use snd_hdac_regmap_update_amp().
*/
static inline int
snd_hdac_regmap_write(struct hdac_device *codec, hda_nid_t nid,
unsigned int verb, unsigned int val)
{
unsigned int cmd = snd_hdac_regmap_encode_verb(nid, verb);
return snd_hdac_regmap_write_raw(codec, cmd, val);
}
/**
* snd_hda_regmap_update - Update a verb value with caching
* @nid: codec NID
* @verb: verb to update
* @mask: bit mask to update
* @val: value to update
*
* For updating an amp value, use snd_hdac_regmap_update_amp().
*/
static inline int
snd_hdac_regmap_update(struct hdac_device *codec, hda_nid_t nid,
unsigned int verb, unsigned int mask,
unsigned int val)
{
unsigned int cmd = snd_hdac_regmap_encode_verb(nid, verb);
return snd_hdac_regmap_update_raw(codec, cmd, mask, val);
}
/**
* snd_hda_regmap_read - Read a verb with caching
* @nid: codec NID
* @verb: verb to read
* @val: pointer to store the value
*
* For reading an amp value, use snd_hda_regmap_get_amp().
*/
static inline int
snd_hdac_regmap_read(struct hdac_device *codec, hda_nid_t nid,
unsigned int verb, unsigned int *val)
{
unsigned int cmd = snd_hdac_regmap_encode_verb(nid, verb);
return snd_hdac_regmap_read_raw(codec, cmd, val);
}
/**
* snd_hdac_regmap_get_amp - Read AMP value
* @codec: HD-audio codec
* @nid: NID to read the AMP value
* @ch: channel (left=0 or right=1)
* @direction: #HDA_INPUT or #HDA_OUTPUT
* @index: the index value (only for input direction)
* @val: the pointer to store the value
*
* Read AMP value. The volume is between 0 to 0x7f, 0x80 = mute bit.
* Returns the value or a negative error.
*/
static inline int
snd_hdac_regmap_get_amp(struct hdac_device *codec, hda_nid_t nid,
int ch, int dir, int idx)
{
unsigned int cmd = snd_hdac_regmap_encode_amp(nid, ch, dir, idx);
int err, val;
err = snd_hdac_regmap_read_raw(codec, cmd, &val);
return err < 0 ? err : val;
}
/**
* snd_hdac_regmap_update_amp - update the AMP value
* @codec: HD-audio codec
* @nid: NID to read the AMP value
* @ch: channel (left=0 or right=1)
* @direction: #HDA_INPUT or #HDA_OUTPUT
* @idx: the index value (only for input direction)
* @mask: bit mask to set
* @val: the bits value to set
*
* Update the AMP value with a bit mask.
* Returns 0 if the value is unchanged, 1 if changed, or a negative error.
*/
static inline int
snd_hdac_regmap_update_amp(struct hdac_device *codec, hda_nid_t nid,
int ch, int dir, int idx, int mask, int val)
{
unsigned int cmd = snd_hdac_regmap_encode_amp(nid, ch, dir, idx);
return snd_hdac_regmap_update_raw(codec, cmd, mask, val);
}
/**
* snd_hdac_regmap_get_amp_stereo - Read stereo AMP values
* @codec: HD-audio codec
* @nid: NID to read the AMP value
* @ch: channel (left=0 or right=1)
* @direction: #HDA_INPUT or #HDA_OUTPUT
* @index: the index value (only for input direction)
* @val: the pointer to store the value
*
* Read stereo AMP values. The lower byte is left, the upper byte is right.
* Returns the value or a negative error.
*/
static inline int
snd_hdac_regmap_get_amp_stereo(struct hdac_device *codec, hda_nid_t nid,
int dir, int idx)
{
unsigned int cmd = snd_hdac_regmap_encode_amp_stereo(nid, dir, idx);
int err, val;
err = snd_hdac_regmap_read_raw(codec, cmd, &val);
return err < 0 ? err : val;
}
/**
* snd_hdac_regmap_update_amp_stereo - update the stereo AMP value
* @codec: HD-audio codec
* @nid: NID to read the AMP value
* @direction: #HDA_INPUT or #HDA_OUTPUT
* @idx: the index value (only for input direction)
* @mask: bit mask to set
* @val: the bits value to set
*
* Update the stereo AMP value with a bit mask.
* The lower byte is left, the upper byte is right.
* Returns 0 if the value is unchanged, 1 if changed, or a negative error.
*/
static inline int
snd_hdac_regmap_update_amp_stereo(struct hdac_device *codec, hda_nid_t nid,
int dir, int idx, int mask, int val)
{
unsigned int cmd = snd_hdac_regmap_encode_amp_stereo(nid, dir, idx);
return snd_hdac_regmap_update_raw(codec, cmd, mask, val);
}
/**
* snd_hdac_regmap_sync_node - sync the widget node attributes
* @codec: HD-audio codec
* @nid: NID to sync
*/
static inline void
snd_hdac_regmap_sync_node(struct hdac_device *codec, hda_nid_t nid)
{
regcache_mark_dirty(codec->regmap);
regcache_sync_region(codec->regmap, nid << 20, ((nid + 1) << 20) - 1);
}
#endif /* __SOUND_HDA_REGMAP_H */
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