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

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Date:   Wed, 8 Jan 2020 11:58:56 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <broonie@...nel.org>, <lgirdwood@...il.com>, <perex@...ex.cz>,
        <tiwai@...e.com>, <digetx@...il.com>, <mperttunen@...dia.com>,
        <gregkh@...uxfoundation.org>, <sboyd@...nel.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <josephl@...dia.com>, <daniel.lezcano@...aro.org>,
        <mmaddireddy@...dia.com>, <markz@...dia.com>,
        <devicetree@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 15/21] ASoC: tegra: Add fallback implementation for
 audio mclk


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@...il.com>
>>> Reviewed-by: Dmitry Osipenko <digetx@...il.com>
>>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>>> ---
>>>   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.

>>> -        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?
>
>>>       }
>>>         /*