Subject: [PATCH 1/2] ARM: kirkwood: fix a not initialized variable in the sound subsystem

From: [email-masked] (Sebastian Hesselbarth)
Date: Tue, 26 Mar 2013 21:39:40 +0100

On 03/26/2013 09:05 PM, Jean-Francois Moine wrote:
> On Tue, 26 Mar 2013 20:41:40 +0100
> Sebastian Hesselbarth<[email-masked]>  wrote:
>
>> On 03/26/2013 07:05 PM, Jean-Francois Moine wrote:
>>> In the function kirkwood_set_rate, in case of a non dco supported rate
>>> and no external clock, the clock source was set to an undefined value.
>>> This patch just displays a message without changing the clock source.
>>>
>>> Signed-off-by: Jean-Francois Moine<[email-masked]>
>>> ---
>>>    sound/soc/kirkwood/kirkwood-i2s.c |    3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/sound/soc/kirkwood/kirkwood-i2s.c b/sound/soc/kirkwood/kirkwood-i2s.c
>>> index c74c890..afca1ec 100644
>>> --- a/sound/soc/kirkwood/kirkwood-i2s.c
>>> +++ b/sound/soc/kirkwood/kirkwood-i2s.c
>>> @@ -118,6 +118,9 @@ static void kirkwood_set_rate(struct snd_soc_dai *dai,
>>>    		clk_set_rate(priv->extclk, 256 * rate);
>>>
>>>    		clks_ctrl = KIRKWOOD_MCLK_SOURCE_EXTCLK;
>>> +	} else {
>>> +		dev_err(dai->dev, "%s: no clock\n", __func__);
>>> +		return;
>>>    	}
>>>    	writel(clks_ctrl, priv->io + KIRKWOOD_CLOCKS_CTRL);
>>>    }
>>
>> NACK.
>>
>> Having no clock at all should be catched during _probe. Moreover,
>> not having the internal clock enabled will lead to system hang due to
>> clock gating. You should rather pass an optional (DT-only) extclk phandle
>> on the second clocks property.

Jean-Francois,

I had a close look at the code and your patch. From a driver
point-of-view kirkwood_set_rate should never been called with
an unsupported rate (see KIRKWOOD_I2S_RATES) when no extclk
is available. With extclk available, the else-if branch will
be taken on rates != KIRKWOOD_I2S_RATES. Actually, your added
else branch will never be taken at all.

I suggest (again) to remove clks_ctrl and move the writel inside
if and else-if branch to cure the compiler warning.

Sebastian