Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock

[Sameer Pujar]

Hi Michael,

On 3/9/2021 8:11 PM, Michael Walle wrote:
> External email: Use caution opening links or attachments
>
>
> Hi,
>
> > If "clocks = <&xxx>" is specified from the CPU or Codec component
> > device node, the clock is not getting enabled. Thus audio playback
> > or capture fails.
> >
> > Fix this by populating "simple_dai->clk" field when clocks property
> > is specified from device node as well. Also tidy up by re-organising
> > conditional statements of parsing logic.
> >
> > Fixes: bb6fc620c2ed ("ASoC: simple-card-utils: add asoc_simple_card_parse_clk()")
> > Cc: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> > Signed-off-by: Sameer Pujar <spujar@xxxxxxxxxx>
> This actually breaks sound on my board
> (arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts).
> The codec on this board (wm8904) has a fixed clock input (only distinct
> frequencies are supported) and uses the FLL of the codec to generate the
> desired sample rate.
>
> It seems that after this patch the clock rate of the codecs clock (rather
> than the FLL) is tried to be changed. Which fails, because it doesn't
> support arbitrary frequencies.

Yes, after the given change the clock will be updated if "*mclk-fs" 
property is specified.

DT you mentioned has property "simple-audio-card,mclk-fs = <256>", which 
means you need a clock that is a function of sample rate. But as per 
above you want a fixed clock for MCLK. I think if you drop this 
property, the clock updates won't happen. Earlier for your case, this 
property was not used at all because the clock handle was not populated.

> -michael
>
> > ---
> >   sound/soc/generic/simple-card-utils.c | 13 ++++++-------
> >   1 file changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
> > index bc0b62e..0754d70 100644
> > --- a/sound/soc/generic/simple-card-utils.c
> > +++ b/sound/soc/generic/simple-card-utils.c
> > @@ -173,16 +173,15 @@ int asoc_simple_parse_clk(struct device *dev,
> >         *  or device's module clock.
> >         */
> >        clk = devm_get_clk_from_child(dev, node, NULL);
> > -     if (!IS_ERR(clk)) {
> > -             simple_dai->sysclk = clk_get_rate(clk);
> > +     if (IS_ERR(clk))
> > +             clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
> >
> > +     if (!IS_ERR(clk)) {
> >                simple_dai->clk = clk;
> > -     } else if (!of_property_read_u32(node, "system-clock-frequency", &val)) {
> > +             simple_dai->sysclk = clk_get_rate(clk);
> > +     } else if (!of_property_read_u32(node, "system-clock-frequency",
> > +                                      &val)) {
> >                simple_dai->sysclk = val;
> > -     } else {
> > -             clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
> > -             if (!IS_ERR(clk))
> > -                     simple_dai->sysclk = clk_get_rate(clk);
> >        }
> >
> >        if (of_property_read_bool(node, "system-clock-direction-out"))
> > --
> > 2.7.4