Re: [PATCH v7 15/21] ASoC: tegra: Add fallback implementation for audio mclk

[Sowjanya Komatineni]

On 1/10/20 2:05 PM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
>
>
> 10.01.2020 20:04, Sowjanya Komatineni ÐÐÑÐÑ:
> > On 1/9/20 10:52 AM, Sowjanya Komatineni wrote:
> > > On 1/7/20 10:28 PM, Sameer Pujar wrote:
> > > > On 1/8/2020 11:18 AM, Sowjanya Komatineni wrote:
> > > > > On 1/7/20 9:34 PM, Sameer Pujar wrote:
> > > > > > On 1/8/2020 9:55 AM, Sowjanya Komatineni wrote:
> > > > > > > mclk is from clk_out_1 which is part of Tegra PMC block and pmc
> > > > > > > clocks
> > > > > > > are moved to Tegra PMC driver with pmc as clock provider and using
> > > > > > > pmc
> > > > > > > clock ids.
> > > > > > >
> > > > > > > New device tree uses clk_out_1 from pmc clock provider.
> > > > > > >
> > > > > > > So, this patch adds implementation for mclk fallback to extern1 when
> > > > > > > retrieving mclk returns -ENOENT to be backward compatible of new
> > > > > > > device
> > > > > > > tree with older kernels.
> > > > > > >
> > > > > > > Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> > > > > > > Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> > > > > > > Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> > > > > > > ---
> > > > > > >    sound/soc/tegra/tegra_asoc_utils.c | 11 ++++++++++-
> > > > > > >    1 file changed, 10 insertions(+), 1 deletion(-)
> > > > > > >
> > > > > > > diff --git a/sound/soc/tegra/tegra_asoc_utils.c
> > > > > > > b/sound/soc/tegra/tegra_asoc_utils.c
> > > > > > > index 9cfebef74870..9a5f81039491 100644
> > > > > > > --- a/sound/soc/tegra/tegra_asoc_utils.c
> > > > > > > +++ b/sound/soc/tegra/tegra_asoc_utils.c
> > > > > > > @@ -183,7 +183,16 @@ int tegra_asoc_utils_init(struct
> > > > > > > tegra_asoc_utils_data *data,
> > > > > > >        data->clk_cdev1 = devm_clk_get(dev, "mclk");
> > > > > > >        if (IS_ERR(data->clk_cdev1)) {
> > > > > > >            dev_err(data->dev, "Can't retrieve clk cdev1\n");
> > > > > > This error print can be moved inside below if, when this actually
> > > > > > meant to be an error condition.
> > > > > Want to show error even if mclk retrieval returns ENOENT to clearly
> > > > > indicate mclk does not exist along with message of falling back to
> > > > > extern1.
> > > > Yes, but falling back essentially means 'mclk' is not available and
> > > > fallback print is not an error.
> > > > Not a major issue though, you can consider updating. Otherwise LGTM.
> > > Will update
> > > > > > > -        return PTR_ERR(data->clk_cdev1);
> > > > > > > +        if (PTR_ERR(data->clk_cdev1) != -ENOENT)
> > > > > > > +            return PTR_ERR(data->clk_cdev1);
> > > > > > > +        /* Fall back to extern1 */
> > > > > > > +        data->clk_cdev1 = devm_clk_get(dev, "extern1");
> > > > > > > +        if (IS_ERR(data->clk_cdev1)) {
> > > > > > > +            dev_err(data->dev, "Can't retrieve clk extern1\n");
> > > > > > > +            return PTR_ERR(data->clk_cdev1);
> > > > > > > +        }
> > > > > > > +
> > > > > > > +        dev_err(data->dev, "Falling back to extern1\n");
> > > > > > This can be a info print?
> > > Will use dev_info
> > > > > > >        }
> > > > > > >          /*
> > > Dmitry/Rob, there was discussion in v3 regarding backporting mclk
> > > fallback.
> > >
> > > Dmitry wanted Rob to confirm on this
> > >
> > > I think openSUSE Leap could be one of those distros that use LTS kernel
> > > with newer device-trees, but that's not 100%. Maybe Rob could help
> > > clarifying that.
> > >
> > > Dmitry/Rob, Can you please confirm if mclk fallback patch need
> > > backport to have new device tree work with old kernels?
> > Dmitry,
> >
> > Can you please confirm if we need to backport this mclk fallback patch?
> Seems only T210 was making use of the CaR's TEGRA*_CLK_CLK_OUT_*, thus
> the backporting isn't needed.
Thanks Dmitry
> Also, please use 'git rebase --exec make ...' to make sure that all
> patches are compiling without problems. The removal of the legacy clock
> IDs should be done after the device-trees changes, otherwise it looks
> like DTBs compilation will fail. It's possible that the order of the
> patches could be changed if Thierry will chose to split this series into
> several pull requests, nevertheless all patches should compile and work
> in the original order.
OK, Will move patches of device tree updates to use new DT ID prior to 
removal of old ID.