diff mbox

[V2] ASoC: tlv320aic3x: Fix codec pll configure bug

Message ID 1340690623-18177-1-git-send-email-gururaja.hebbar@ti.com (mailing list archive)
State Awaiting Upstream
Headers show

Commit Message

Hebbar, Gururaja June 26, 2012, 6:03 a.m. UTC
In sound/soc/codecs/tlv320aic3x.c

        data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG);
        snd_soc_write(codec, AIC3X_PLL_PROGA_REG,
                      data | (pll_p << PLLP_SHIFT));

In the above code, pll-p value is OR'ed with previous value without
clearing it. Bug is not seen if pll-p value doesn't change across
Sampling frequency.

However on some platforms (like AM335x EVM-SK), pll-p may have different
values across different sampling frequencies. In such case, above code
configures the pll with a wrong value.
Because of this bug, when a audio stream is played with pll value
different from previous stream, audio is heard as differently.

Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@ti.com>
---
chnages in V2:
	modify subject to indicate ASOC and codec as tlv320aic3x

 sound/soc/codecs/tlv320aic3x.c |    2 +-
 sound/soc/codecs/tlv320aic3x.h |    1 +
 2 files changed, 2 insertions(+), 1 deletions(-)

Comments

Jiri Prchal June 26, 2012, 9:01 a.m. UTC | #1
Hi Gururaja,
shouldn't be better to use:

snd_soc_update_bits(codec, AIC3X_PLL_PROGA_REG, PLLP_MASK, pll_p);

instead of "read mask write" ?
Even at this place you don't need to keep rest of register (PLL_Q and PLL_enable), so yust writing is OK.

snd_soc_write(codec, AIC3X_PLL_PROGA_REG, pll_p << PLLP_SHIFT);


Dne 26.6.2012 08:03, Hebbar, Gururaja napsal(a):
> In sound/soc/codecs/tlv320aic3x.c
>
>          data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG);
>          snd_soc_write(codec, AIC3X_PLL_PROGA_REG,
>                        data | (pll_p<<  PLLP_SHIFT));
>
> In the above code, pll-p value is OR'ed with previous value without
> clearing it. Bug is not seen if pll-p value doesn't change across
> Sampling frequency.
>
> However on some platforms (like AM335x EVM-SK), pll-p may have different
> values across different sampling frequencies. In such case, above code
> configures the pll with a wrong value.
> Because of this bug, when a audio stream is played with pll value
> different from previous stream, audio is heard as differently.
>
> Signed-off-by: Hebbar, Gururaja<gururaja.hebbar@ti.com>
> ---
> chnages in V2:
> 	modify subject to indicate ASOC and codec as tlv320aic3x
>
>   sound/soc/codecs/tlv320aic3x.c |    2 +-
>   sound/soc/codecs/tlv320aic3x.h |    1 +
>   2 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/sound/soc/codecs/tlv320aic3x.c b/sound/soc/codecs/tlv320aic3x.c
> index d0dbac1..8c1977b 100644
> --- a/sound/soc/codecs/tlv320aic3x.c
> +++ b/sound/soc/codecs/tlv320aic3x.c
> @@ -963,7 +963,7 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream,
>   	}
>
>   found:
> -	data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG);
> +	data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG)&  ~PLLP_MASK;
>   	snd_soc_write(codec, AIC3X_PLL_PROGA_REG,
>   		      data | (pll_p<<  PLLP_SHIFT));
>   	snd_soc_write(codec, AIC3X_OVRF_STATUS_AND_PLLR_REG,
> diff --git a/sound/soc/codecs/tlv320aic3x.h b/sound/soc/codecs/tlv320aic3x.h
> index 06a1978..16d9999 100644
> --- a/sound/soc/codecs/tlv320aic3x.h
> +++ b/sound/soc/codecs/tlv320aic3x.h
> @@ -166,6 +166,7 @@
>
>   /* PLL registers bitfields */
>   #define PLLP_SHIFT		0
> +#define PLLP_MASK		7
>   #define PLLQ_SHIFT		3
>   #define PLLR_SHIFT		0
>   #define PLLJ_SHIFT		2
Hebbar, Gururaja June 26, 2012, 2:07 p.m. UTC | #2
On Tue, Jun 26, 2012 at 14:24:03, Mark Brown wrote:
> On Tue, Jun 26, 2012 at 11:33:43AM +0530, Hebbar, Gururaja wrote:
> > In sound/soc/codecs/tlv320aic3x.c
> > 
> >         data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG);
> >         snd_soc_write(codec, AIC3X_PLL_PROGA_REG,
> >                       data | (pll_p << PLLP_SHIFT));
> > 
> > In the above code, pll-p value is OR'ed with previous value without
> > clearing it. Bug is not seen if pll-p value doesn't change across
> > Sampling frequency.
> 
> A better fix is to change the code to use snd_soc_update_bits() rather
> than open code it.  This is more idiomatic and will suppress writes if
> they don't change anything.
> 

Sure will resend the patch. Thanks for the review


Regards, 
Gururaja
diff mbox

Patch

diff --git a/sound/soc/codecs/tlv320aic3x.c b/sound/soc/codecs/tlv320aic3x.c
index d0dbac1..8c1977b 100644
--- a/sound/soc/codecs/tlv320aic3x.c
+++ b/sound/soc/codecs/tlv320aic3x.c
@@ -963,7 +963,7 @@  static int aic3x_hw_params(struct snd_pcm_substream *substream,
 	}
 
 found:
-	data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG);
+	data = snd_soc_read(codec, AIC3X_PLL_PROGA_REG) & ~PLLP_MASK;
 	snd_soc_write(codec, AIC3X_PLL_PROGA_REG,
 		      data | (pll_p << PLLP_SHIFT));
 	snd_soc_write(codec, AIC3X_OVRF_STATUS_AND_PLLR_REG,
diff --git a/sound/soc/codecs/tlv320aic3x.h b/sound/soc/codecs/tlv320aic3x.h
index 06a1978..16d9999 100644
--- a/sound/soc/codecs/tlv320aic3x.h
+++ b/sound/soc/codecs/tlv320aic3x.h
@@ -166,6 +166,7 @@ 
 
 /* PLL registers bitfields */
 #define PLLP_SHIFT		0
+#define PLLP_MASK		7
 #define PLLQ_SHIFT		3
 #define PLLR_SHIFT		0
 #define PLLJ_SHIFT		2