[alsa-devel] [PATCH] ASoC: OMAP: mcbsp: ensure that CLKX and CLKR are not used as ouput pins when they are used as input clock for the SRG.

[Peter Ujfalusi]

On 01/16/2015 12:28 AM, Thomas Niederprüm wrote:
> This patch fixes faulty behaviour in a setup where the input clock for
> the SRG is fed through the CLKR pin but the McBSP is configured to be
> master (SND_SOC_DAIFMT_CBS_CFS). In that case of course CLKR must not be
> configured as output pin. Otherwise the input clock is messed up
> horribly. The same reasoning applies if CLKX is configured as input for
> the SRG.

If CLKX/CLKR is used as input clock for McBSP then the CBS_CFS is not valid.
In this case you need to use CBM_CFS.

> 
> Signed-off-by: Thomas Niederprüm <niederp at physik.uni-kl.de>
> ---
>  sound/soc/omap/omap-mcbsp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
> index bd3ef2a..c89f562 100644
> --- a/sound/soc/omap/omap-mcbsp.c
> +++ b/sound/soc/omap/omap-mcbsp.c
> @@ -530,8 +530,12 @@ static int omap_mcbsp_dai_set_dai_sysclk(struct snd_soc_dai *cpu_dai,
>  
>  	case OMAP_MCBSP_SYSCLK_CLKX_EXT:
>  		regs->srgr2	|= CLKSM;
> +		regs->pcr0	|= SCLKME;
> +		regs->pcr0	&= ~CLKXM;
> +		break;
>  	case OMAP_MCBSP_SYSCLK_CLKR_EXT:
>  		regs->pcr0	|= SCLKME;
> +		regs->pcr0	&= ~CLKRM;
>  		break;
>  	default:
>  		err = -ENODEV;
> 


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