[RFC][PATCH] ASoC: Avoid writing to WM8971_RESET in wm8971_resume

[RFC][PATCH] ASoC: Avoid writing to WM8971_RESET in wm8971_resume

[Axel Lin]

Writing to WM8971_RESET resets all registers to the default state.
Thus we should avoid writing to WM8971_RESET on resume.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
Hi,
While reading the code, I don't understand why we need to do (in wm8971_resume):

for (i = 0; i < ARRAY_SIZE(wm8971_reg); i++) {
        if (i + 1 == WM8971_RESET)
                continue;

My understanding is that we want to avoid writing to WM8971_RESET on resume.
Thus I send this patch for review.
I don't have the hardware for testing, I'd appreciate if someone can test this patch.

Thanks,
Axel

 sound/soc/codecs/wm8971.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/sound/soc/codecs/wm8971.c b/sound/soc/codecs/wm8971.c
index 572bb80..7ec4165 100644
--- a/sound/soc/codecs/wm8971.c
+++ b/sound/soc/codecs/wm8971.c
@@ -612,7 +612,7 @@ static int wm8971_resume(struct snd_soc_codec *codec)
 
 	/* Sync reg_cache with the hardware */
 	for (i = 0; i < ARRAY_SIZE(wm8971_reg); i++) {
-		if (i + 1 == WM8971_RESET)
+		if (i == WM8971_RESET)
 			continue;
 		data[0] = (i << 1) | ((cache[i] >> 8) & 0x0001);
 		data[1] = cache[i] & 0x00ff;
-- 
1.7.4.1

Re: [RFC][PATCH] ASoC: Avoid writing to WM8971_RESET in wm8971_resume

[Mark Brown]

On Tue, Oct 04, 2011 at 07:44:22AM +0800, Axel Lin wrote:

> While reading the code, I don't understand why we need to do (in wm8971_resume):
> 
> for (i = 0; i < ARRAY_SIZE(wm8971_reg); i++) {
>         if (i + 1 == WM8971_RESET)
>                 continue;
> 
> My understanding is that we want to avoid writing to WM8971_RESET on resume.

Yeah, this looks like a leftover from some older code which omitted
register zero from the cache for some small memory savings.  Now things
are using the standard cache code rather than custom cache code this
is buggy.

Applied, thanks.