[alsa-devel] [RFC PATCH] ASoC: omap-mcbsp: Add support for highter rate up to 384000

[Michael Trimarchi]

Hi

On Fri, Aug 09, 2013 at 08:18:23AM +0300, Peter Ujfalusi wrote:
> On 08/08/2013 02:04 PM, Michael Trimarchi wrote:
> > On Thu, Aug 08, 2013 at 01:51:25PM +0300, Peter Ujfalusi wrote:
> >> On 08/07/2013 09:28 PM, Michael Trimarchi wrote:
> >>> Add support for highter rate up to 384000Khz. There are codecs in the
> >>> market that can play up to this frequency.
> >>> Test was done just with:
> >>>
> >>> #define OMAP_MCBSP_RATES	(SNDRV_PCM_RATE_8000_192000)
> >>>
> >>> playing wav file 32bit/192000Khz stereo. Some glitch has observed
> >>> but this should depend on the selected min buffer bytes that was
> >>> left untouched in aplay and in the omap-pcm driver.
> >>>
> >>> Signed-off-by: Michael Trimarchi <michael at amarulasolutions.com>
> >>> ---
> >>>  sound/soc/omap/omap-mcbsp.c |    8 +++++++-
> >>>  1 file changed, 7 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
> >>> index 7483efb..1e95f6a 100644
> >>> --- a/sound/soc/omap/omap-mcbsp.c
> >>> +++ b/sound/soc/omap/omap-mcbsp.c
> >>> @@ -39,7 +39,9 @@
> >>>  #include "mcbsp.h"
> >>>  #include "omap-mcbsp.h"
> >>>  
> >>> -#define OMAP_MCBSP_RATES	(SNDRV_PCM_RATE_8000_96000)
> >>> +#define OMAP_MCBSP_RATES	(SNDRV_PCM_RATE_8000_192000 |		\
> >>
> >> I think only this change is enough for what you want to achieve.
> >>
> >>> +				 SNDRV_PCM_RATE_CONTINUOUS |		\
> >>> +				 SNDRV_PCM_RATE_KNOT)
> >>
> >> The _KNOT is for sure not needed and I would not set the CONTINUOUS either.
> > 
> > pcm5102pw is a codec that support 384000 rate so I think that PCM_RATE_KNOT
> > is requested for such rate. Correct?
> 
> Yes, looks that way. I had overlooked the 384000 KHz...
> 

Ok, I will do it better

> >>
> >>>  
> >>>  #define OMAP_MCBSP_SOC_SINGLE_S16_EXT(xname, xmin, xmax, \
> >>>  	xhandler_get, xhandler_put) \
> >>> @@ -574,11 +576,15 @@ static struct snd_soc_dai_driver omap_mcbsp_dai = {
> >>>  		.channels_max = 16,
> >>>  		.rates = OMAP_MCBSP_RATES,
> >>>  		.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE,
> >>> +		.rate_min = 8000,
> >>> +		.rate_max = 384000,
> >>
> >> Why you want to limit the rates here?
> >>
> > 
> > I didn't find in the market somenthing up to 384000.
> 
> Sure, but it is not correct to say that McBSP supports rates up to 384000.
> McBSP have constraint on the BCLK speed up to 48MHz. So while
> 32bit/stereo/384000 is OK, 32bit/4channel/384000 is not, but
> 16bit/4channel/384000 is again good.
> When McBSP is master we have a check for the clock speed. We might need to
> have similar for McBSP slave mode, but I don't think we are going to hit the
> 48MHz limit anyways.

Should be possible to consider this limitation of the McBSP clock speed.
I'm going to take a look on this. I will send another patch

Michael


> 
> 
> > 
> > Michael
> > 
> >>>  	},
> >>>  	.capture = {
> >>>  		.channels_min = 1,
> >>>  		.channels_max = 16,
> >>>  		.rates = OMAP_MCBSP_RATES,
> >>> +		.rate_min = 8000,
> >>> +		.rate_max = 384000,
> >>
> >> Same here, do not set these.
> >>
> >>>  		.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE,
> >>>  	},
> >>>  	.ops = &mcbsp_dai_ops,
> >>>
> >>
> >>
> >> -- 
> >> Péter
> > 
> 
> 
> -- 
> Péter

-- 
| Michael Nazzareno Trimarchi                     Amarula Solutions BV |
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