[PATCH] ALSA: ASoC: McASP: Fix data rotation for playback. Enables 24bit audio playback

[PATCH] ALSA: ASoC: McASP: Fix data rotation for playback. Enables 24bit audio playback

[Michal Bachraty]

Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>
---
 sound/soc/davinci/davinci-mcasp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 13f8d73..a03bece 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -626,7 +626,7 @@ static int davinci_config_channel_size(struct davinci_audio_dev *dev,
 				       int word_length)
 {
 	u32 fmt;
-	u32 rotate = (32 - word_length) / 4;
+	u32 rotate = (word_length / 4) & 0x7;
 	u32 mask = (1ULL << word_length) - 1;
 
 	/*
-- 
1.7.9.5

RE: [alsa-devel] [PATCH] ALSA: ASoC: McASP: Fix data rotation for playback. Enables 24bit audio playback

[Hebbar, Gururaja]

On Tue, Jan 15, 2013 at 20:11:00, Michal Bachraty wrote:
> Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>

Even simple patches need a simple changelog.
Add a brief description about what & why it is done?


> ---
>  sound/soc/davinci/davinci-mcasp.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
> index 13f8d73..a03bece 100644
> --- a/sound/soc/davinci/davinci-mcasp.c
> +++ b/sound/soc/davinci/davinci-mcasp.c
> @@ -626,7 +626,7 @@ static int davinci_config_channel_size(struct davinci_audio_dev *dev,
>  				       int word_length)
>  {
>  	u32 fmt;
> -	u32 rotate = (32 - word_length) / 4;
> +	u32 rotate = (word_length / 4) & 0x7;
>  	u32 mask = (1ULL << word_length) - 1;
>  
>  	/*
> -- 
> 1.7.9.5
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> 


Regards, 
Gururaja

Re: [alsa-devel] [PATCH] ALSA: ASoC: McASP: Fix data rotation for playback. Enables 24bit audio playback

[Michal Bachraty]

On Friday, January 18, 2013 08:22:53 Hebbar, Gururaja wrote:
> On Tue, Jan 15, 2013 at 20:11:00, Michal Bachraty wrote:
> > Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>
> 
> Even simple patches need a simple changelog.
> Add a brief description about what & why it is done?
> 

Hi Gurujaja,

> > -	u32 rotate = (32 - word_length) / 4;
This implementation is wrong, but it works only for 16, or 32 bit audio data.
(rotation for 16 or 32 bit is same as in code I present) Mcasp rotated data in 
4 bits (max value 0x7)and then masks them . That data are sended to i2s bus. 
For 24 bit or 20 bit or other data formats, this code rotates data badly and 
you hear somethink like noise.  You need to use
> > +	u32 rotate = (word_length / 4) & 0x7;
to proper data rotation. 

Regards,
Michal

RE: [alsa-devel] [PATCH] ALSA: ASoC: McASP: Fix data rotation for playback. Enables 24bit audio playback

[Hebbar, Gururaja]

On Fri, Jan 18, 2013 at 14:13:40, Michal Bachraty wrote:
> On Friday, January 18, 2013 08:22:53 Hebbar, Gururaja wrote:
> > On Tue, Jan 15, 2013 at 20:11:00, Michal Bachraty wrote:
> > > Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>
> > 
> > Even simple patches need a simple changelog.
> > Add a brief description about what & why it is done?
> > 
> 
> Hi Gurujaja,
> 
> > > -	u32 rotate = (32 - word_length) / 4;
> This implementation is wrong, but it works only for 16, or 32 bit audio data.
> (rotation for 16 or 32 bit is same as in code I present) Mcasp rotated data in 
> 4 bits (max value 0x7)and then masks them . That data are sended to i2s bus. 
> For 24 bit or 20 bit or other data formats, this code rotates data badly and 
> you hear somethink like noise.  You need to use
> > > +	u32 rotate = (word_length / 4) & 0x7;
> to proper data rotation. 

Correct. Now can you add the above info into the patch and re-submit. 
That way when users sees this patch, they will get all the info needed.

> 
> Regards,
> Michal
> 
> 


Regards, 
Gururaja