[RFC][PATCH] ASoC: Fix sync reg_cache with the hardware in wm8990_resume

[RFC][PATCH] ASoC: Fix sync reg_cache with the hardware in wm8990_resume

[Axel Lin]

Current code has off-by-one bug of checking WM8990_RESET.
Besides, according to wm8990 datasheet (2-wire serial control mode):
A control word consists of 24 bits. The first 8 bits are address bits,
the remaining 16 bits are data bits.
Current code uses 7 bits address bits and 9 bits data bits which is incorrect.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
I'd appreciate if someone can test it.
I'm a little bit confused if this fix is correct, why there is no bug report so far.
If I'm wrong, please kindly let me know.
Thanks,
Axel
 sound/soc/codecs/wm8990.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/wm8990.c b/sound/soc/codecs/wm8990.c
index 100aeee..5546f5a 100644
--- a/sound/soc/codecs/wm8990.c
+++ b/sound/soc/codecs/wm8990.c
@@ -1320,16 +1320,17 @@ static int wm8990_suspend(struct snd_soc_codec *codec, pm_message_t state)
 static int wm8990_resume(struct snd_soc_codec *codec)
 {
 	int i;
-	u8 data[2];
+	u8 data[3];
 	u16 *cache = codec->reg_cache;
 
 	/* Sync reg_cache with the hardware */
 	for (i = 0; i < ARRAY_SIZE(wm8990_reg); i++) {
-		if (i + 1 == WM8990_RESET)
+		if (i == WM8990_RESET)
 			continue;
-		data[0] = ((i + 1) << 1) | ((cache[i] >> 8) & 0x0001);
-		data[1] = cache[i] & 0x00ff;
-		codec->hw_write(codec->control_data, data, 2);
+		data[0] = i;
+		data[1] = (cache[i] & 0xFF00) >> 8;
+		data[2] = cache[i] & 0x00FF;
+		codec->hw_write(codec->control_data, data, 3);
 	}
 
 	wm8990_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
-- 
1.7.4.1

Re: [RFC][PATCH] ASoC: Fix sync reg_cache with the hardware in wm8990_resume

[Mark Brown]

On Wed, Oct 05, 2011 at 06:16:49PM +0800, Axel Lin wrote:
> Current code has off-by-one bug of checking WM8990_RESET.
> Besides, according to wm8990 datasheet (2-wire serial control mode):
> A control word consists of 24 bits. The first 8 bits are address bits,
> the remaining 16 bits are data bits.
> Current code uses 7 bits address bits and 9 bits data bits which is incorrect.

We should just convert drivers like this to snd_soc_cache_sync().

Re: [RFC][PATCH] ASoC: Fix sync reg_cache with the hardware in wm8990_resume

[Axel Lin]

2011/10/5 Mark Brown <broonie@opensource.wolfsonmicro.com>:
> On Wed, Oct 05, 2011 at 06:16:49PM +0800, Axel Lin wrote:
>> Current code has off-by-one bug of checking WM8990_RESET.
>> Besides, according to wm8990 datasheet (2-wire serial control mode):
>> A control word consists of 24 bits. The first 8 bits are address bits,
>> the remaining 16 bits are data bits.
>> Current code uses 7 bits address bits and 9 bits data bits which is incorrect.
>
> We should just convert drivers like this to snd_soc_cache_sync().

Yes. It would be better convert it to snd_soc_cache_sync().
Just think this patch may be useful for 3.1 or earlier kernel version.

Axel