[PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Dimitris Papastamos]

This is primarily needed to avoid writing back to the cache
whenever we are syncing the cache with the hardware.  This gives a
performance benefit especially for large register maps.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 include/sound/soc.h   |    1 +
 sound/soc/soc-cache.c |   36 ++++++++++++++++++++++++------------
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 74921f2..5e19644 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -463,6 +463,7 @@ struct snd_soc_codec {
 	/* runtime */
 	struct snd_ac97 *ac97;  /* for ad-hoc ac97 devices */
 	unsigned int active;
+	unsigned int cache_bypass:1; /* Suppress access to the cache */
 	unsigned int cache_only:1;  /* Suppress writes to hardware */
 	unsigned int cache_sync:1; /* Cache needs to be synced to hardware */
 	unsigned int suspended:1; /* Codec is in suspend PM state */
diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 8c2a21a..799e376 100644
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -25,7 +25,8 @@ static unsigned int snd_soc_4_12_read(struct snd_soc_codec *codec,
 	unsigned int val;
 
 	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg)) {
+		snd_soc_codec_volatile_register(codec, reg) ||
+		codec->cache_bypass) {
 			if (codec->cache_only)
 				return -1;
 
@@ -49,7 +50,8 @@ static int snd_soc_4_12_write(struct snd_soc_codec *codec, unsigned int reg,
 	data[1] = value & 0x00ff;
 
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -106,7 +108,8 @@ static unsigned int snd_soc_7_9_read(struct snd_soc_codec *codec,
 	unsigned int val;
 
 	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg)) {
+		snd_soc_codec_volatile_register(codec, reg) ||
+		codec->cache_bypass) {
 			if (codec->cache_only)
 				return -1;
 
@@ -130,7 +133,8 @@ static int snd_soc_7_9_write(struct snd_soc_codec *codec, unsigned int reg,
 	data[1] = value & 0x00ff;
 
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -191,7 +195,8 @@ static int snd_soc_8_8_write(struct snd_soc_codec *codec, unsigned int reg,
 	data[1] = value & 0xff;
 
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -216,7 +221,8 @@ static unsigned int snd_soc_8_8_read(struct snd_soc_codec *codec,
 
 	reg &= 0xff;
 	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg)) {
+		snd_soc_codec_volatile_register(codec, reg) ||
+		codec->cache_bypass) {
 			if (codec->cache_only)
 				return -1;
 
@@ -271,7 +277,8 @@ static int snd_soc_8_16_write(struct snd_soc_codec *codec, unsigned int reg,
 	data[2] = value & 0xff;
 
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -295,7 +302,8 @@ static unsigned int snd_soc_8_16_read(struct snd_soc_codec *codec,
 	unsigned int val;
 
 	if (reg >= codec->driver->reg_cache_size ||
-	    snd_soc_codec_volatile_register(codec, reg)) {
+	    snd_soc_codec_volatile_register(codec, reg) ||
+	    codec->cache_bypass) {
 		if (codec->cache_only)
 			return -1;
 
@@ -450,7 +458,8 @@ static unsigned int snd_soc_16_8_read(struct snd_soc_codec *codec,
 
 	reg &= 0xff;
 	if (reg >= codec->driver->reg_cache_size ||
-		snd_soc_codec_volatile_register(codec, reg)) {
+		snd_soc_codec_volatile_register(codec, reg) ||
+		codec->cache_bypass) {
 			if (codec->cache_only)
 				return -1;
 
@@ -476,7 +485,8 @@ static int snd_soc_16_8_write(struct snd_soc_codec *codec, unsigned int reg,
 
 	reg &= 0xff;
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
@@ -568,7 +578,8 @@ static unsigned int snd_soc_16_16_read(struct snd_soc_codec *codec,
 	unsigned int val;
 
 	if (reg >= codec->driver->reg_cache_size ||
-	    snd_soc_codec_volatile_register(codec, reg)) {
+	    snd_soc_codec_volatile_register(codec, reg) ||
+	    codec->cache_bypass) {
 		if (codec->cache_only)
 			return -1;
 
@@ -595,7 +606,8 @@ static int snd_soc_16_16_write(struct snd_soc_codec *codec, unsigned int reg,
 	data[3] = value & 0xff;
 
 	if (!snd_soc_codec_volatile_register(codec, reg) &&
-		reg < codec->driver->reg_cache_size) {
+		reg < codec->driver->reg_cache_size &&
+		!codec->cache_bypass) {
 		ret = snd_soc_cache_write(codec, reg, value);
 		if (ret < 0)
 			return -1;
-- 
1.7.4

[PATCH 2/2 2.6.38] ASoC: soc-cache: Apply the cache_bypass option

[Dimitris Papastamos]

Incorporate the use of the cache_bypass functionality in the
syncing functions.  The snd_soc_flat_cache_sync() need not be
hooked as there is no performance benefit from using the
cache_bypass option.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 sound/soc/soc-cache.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 799e376..9d43bee 100644
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -847,7 +847,9 @@ static int snd_soc_rbtree_cache_sync(struct snd_soc_codec *codec)
 		ret = snd_soc_cache_read(codec, rbnode->reg, &val);
 		if (ret)
 			return ret;
+		codec->cache_bypass = 1;
 		ret = snd_soc_write(codec, rbnode->reg, val);
+		codec->cache_bypass = 0;
 		if (ret)
 			return ret;
 		dev_dbg(codec->dev, "Synced register %#x, value = %#x\n",
@@ -1134,7 +1136,9 @@ static int snd_soc_lzo_cache_sync(struct snd_soc_codec *codec)
 		ret = snd_soc_cache_read(codec, i, &val);
 		if (ret)
 			return ret;
+		codec->cache_bypass = 1;
 		ret = snd_soc_write(codec, i, val);
+		codec->cache_bypass = 0;
 		if (ret)
 			return ret;
 		dev_dbg(codec->dev, "Synced register %#x, value = %#x\n",
-- 
1.7.4

Re: [PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Mark Brown]

On Fri, Feb 11, 2011 at 02:54:01PM +0000, Dimitris Papastamos wrote:
> This is primarily needed to avoid writing back to the cache
> whenever we are syncing the cache with the hardware.  This gives a
> performance benefit especially for large register maps.

Hrm, this is a rather large and invasive patch to be applying as part of
a bug fix for a specific driver this late in the release process.  Can
we do something driver specific for the 2.6.38 release?

Re: [PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Dimitris Papastamos]

On Fri, Feb 11, 2011 at 03:18:26PM +0000, Mark Brown wrote:
> On Fri, Feb 11, 2011 at 02:54:01PM +0000, Dimitris Papastamos wrote:
> > This is primarily needed to avoid writing back to the cache
> > whenever we are syncing the cache with the hardware.  This gives a
> > performance benefit especially for large register maps.
> 
> Hrm, this is a rather large and invasive patch to be applying as part of
> a bug fix for a specific driver this late in the release process.  Can
> we do something driver specific for the 2.6.38 release?

Em, make WM8994_POWER_MANAGEMENT_5 a volatile register?  That is sort of
a hack but I can't think of anything else.

Thanks,
Dimitris

Re: [PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Dimitris Papastamos]

On Fri, Feb 11, 2011 at 03:21:03PM +0000, Dimitris Papastamos wrote:
> On Fri, Feb 11, 2011 at 03:18:26PM +0000, Mark Brown wrote:
> > On Fri, Feb 11, 2011 at 02:54:01PM +0000, Dimitris Papastamos wrote:
> > > This is primarily needed to avoid writing back to the cache
> > > whenever we are syncing the cache with the hardware.  This gives a
> > > performance benefit especially for large register maps.
> > 
> > Hrm, this is a rather large and invasive patch to be applying as part of
> > a bug fix for a specific driver this late in the release process.  Can
> > we do something driver specific for the 2.6.38 release?
> 
> Em, make WM8994_POWER_MANAGEMENT_5 a volatile register?  That is sort of
> a hack but I can't think of anything else.

Now that I think about it, that won't work.  We still need to be able to 
sync the other bitfields in that register on resume.

Thanks,
Dimitris

Re: [PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Dimitris Papastamos]

On Fri, Feb 11, 2011 at 03:18:26PM +0000, Mark Brown wrote:
> On Fri, Feb 11, 2011 at 02:54:01PM +0000, Dimitris Papastamos wrote:
> > This is primarily needed to avoid writing back to the cache
> > whenever we are syncing the cache with the hardware.  This gives a
> > performance benefit especially for large register maps.
> 
> Hrm, this is a rather large and invasive patch to be applying as part of
> a bug fix for a specific driver this late in the release process.  Can
> we do something driver specific for the 2.6.38 release?

Would this be acceptable?  In wm8994_resume():

/* force a HW read */
val = wm8994_reg_read(codec->control_data, WM8994_POWER_MANAGEMENT_5);

instead of the call to snd_soc_read().

Thanks,
Dimitris

Re: [PATCH 1/2 2.6.38] ASoC: soc-cache: Introduce the cache_bypass option

[Mark Brown]

On Fri, Feb 11, 2011 at 03:46:54PM +0000, Dimitris Papastamos wrote:

> Would this be acceptable?  In wm8994_resume():

> /* force a HW read */
> val = wm8994_reg_read(codec->control_data, WM8994_POWER_MANAGEMENT_5);

> instead of the call to snd_soc_read().

Yes, that looks good.  We can then update to use the APIs more normally
in 2.6.39.