[alsa-devel] [PATCH] ASoC: Allow codecs to override register display

[Takashi Iwai]

At Fri, 18 Jul 2008 11:23:09 -0400,
Jon Smirl wrote:
> 
> On 7/18/08, Mark Brown <broonie at opensource.wolfsonmicro.com> wrote:
> > Some codecs have unusual features in their register maps such as very
> >  large registers representing arrays of coefficients. Support these
> >  codecs in the register cache sysfs file by allowing them to provide a
> >  function register_display() overriding the default output for register
> >  contents.
> 
> My address space is sparse like Grant's. How about display_register()
> returning -1 to skip the register address. The part printing the
> address would need to be suppressed too.
> count += sprintf(buf + count, "%2x: ", i);
> 
> Alternatively you could just make the entire codec_reg_show() overridable.

Yes, I agree.  For non-standard register maps, provide its own
codec_reg_show().

> Might want to add another parameter for cached/uncached. Then we could
> make a debug option to add the non-cached display.

That makes sense, too.

> This loop needs to be protected to not write over the sysfs limit of
> PAGE_SIZE in the result. I think you will corrupt memory if PAGE_SIZE
> is exceeded.

Right.  So far, it's been OK since the number of registers is
relatively small.


Takashi

> >  Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> >  ---
> >   include/sound/soc.h  |    1 +
> >   sound/soc/soc-core.c |   14 ++++++++++----
> >   2 files changed, 11 insertions(+), 4 deletions(-)
> >
> >  diff --git a/include/sound/soc.h b/include/sound/soc.h
> >  index 1890d87..8b1a3e7 100644
> >  --- a/include/sound/soc.h
> >  +++ b/include/sound/soc.h
> >  @@ -410,6 +410,7 @@ struct snd_soc_codec {
> >         void *control_data; /* codec control (i2c/3wire) data */
> >         unsigned int (*read)(struct snd_soc_codec *, unsigned int);
> >         int (*write)(struct snd_soc_codec *, unsigned int, unsigned int);
> >  +       int (*display_register)(struct snd_soc_codec *, char *, unsigned int);
> >         hw_write_t hw_write;
> >         hw_read_t hw_read;
> >         void *reg_cache;
> >  diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> >  index 83f1190..49532d9 100644
> >  --- a/sound/soc/soc-core.c
> >  +++ b/sound/soc/soc-core.c
> >  @@ -970,10 +970,16 @@ static ssize_t codec_reg_show(struct device *dev,
> >                 step = codec->reg_cache_step;
> >
> >         count += sprintf(buf, "%s registers\n", codec->name);
> >  -       for (i = 0; i < codec->reg_cache_size; i += step)
> >  -               count += sprintf(buf + count, "%2x: %4x\n", i,
> >  -                       codec->read(codec, i));
> >  -
> >  +       for (i = 0; i < codec->reg_cache_size; i += step) {
> >  +               count += sprintf(buf + count, "%2x: ", i);
> >  +               if (codec->display_register)
> >  +                       count += codec->display_register(codec,
> >  +                                                        buf + count, i);
> >  +               else
> >  +                       count += sprintf(buf + count, "%4x",
> >  +                                        codec->read(codec, i));
> >  +               count += sprintf(buf + count, "\n");
> >  +       }
> >         return count;
> >   }
> >   static DEVICE_ATTR(codec_reg, 0444, codec_reg_show, NULL);
> >
> > --
> >  1.5.6.3
> >
> >
> 
> 
> -- 
> Jon Smirl
> jonsmirl at gmail.com
>