On 05/20/2014 02:40 PM, Sylwester Nawrocki wrote:
> On 20/05/14 07:14, Tushar Behera wrote:
>> On 05/19/2014 11:00 PM, Sylwester Nawrocki wrote:
>>> This patch adds support for setting source clock of the "Core CLK"
>>> of the IIS Multi Audio Interface.
>>>
>>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
>>> ---
>>> sound/soc/samsung/i2s.c | 4 ++++
>>> sound/soc/samsung/i2s.h | 1 +
>>> 2 files changed, 5 insertions(+)
>>>
>>> diff --git a/sound/soc/samsung/i2s.c b/sound/soc/samsung/i2s.c
>>> index 048ead9..ae02811 100644
>>> --- a/sound/soc/samsung/i2s.c
>>> +++ b/sound/soc/samsung/i2s.c
>>> @@ -451,6 +451,10 @@ static int i2s_set_sysclk(struct snd_soc_dai *dai,
>>> u32 mod = readl(i2s->addr + I2SMOD);
>>>
>>> switch (clk_id) {
>>> + case SAMSUNG_I2S_OPCLK:
>>> + mod &= ~MOD_OPCLK_MASK;
>>> + mod |= dir;
>>
>> I am assuming here that dir is one of SND_SOC_CLOCK_IN or
>> SND_SOC_CLOCK_OUT. In that case, you need to take care of offset (30).
>
> And that's not a correct assumption. I also got similarly confused when
> first seeing this in our downstream kernels. 'dir' is supposed to be one
> of the MOD_OPCLK_* constants, as defined in sound/soc/samsung/i2s-regs.h.
>
> #define MOD_OPCLK_CDCLK_OUT (0 << 30)
> #define MOD_OPCLK_CDCLK_IN (1 << 30)
> #define MOD_OPCLK_BCLK_OUT (2 << 30)
> #define MOD_OPCLK_PCLK (3 << 30)
> #define MOD_OPCLK_MASK (3 << 30)
>
> So the clock is reconfigured with calls like:
> snd_soc_dai_set_sysclk(cpu_dai, SAMSUNG_I2S_OPCLK, 0, MOD_OPCLK_PCLK);
>
Ok.
>> Also the value of this bit-field doesn't match with SND_SOC_CLOCK_XXX
>> macros.
>>
>> Bit-field (2'b):
>> 00 Codec Clock out
>> 01 Codec Clock in
>> 10 Bit clock out
>> 11 Audio bus clock
>>
>> Value of macros:
>> SND_SOC_CLOCK_IN 0
>> SND_SOC_CLOCK_OUT 1
>
>> In the manual, this field is suggested to be Audio bus clock always. Is
>> there an use-case where we might need to update this?
>
> I've checked couple boards and AFAICS we're always setting MOD_OPCLK_PCLK,
> however it's still different from the default value after reset -
> MOD_OPCLK_CDCLK_OUT.
> So how do you think this should be addressed ? Isn't it better to give
> options to the machine drivers to alter these clock settings, rather than
> hard coding it in the I2S driver ? Let's not forget it covers multiple
> Samsung SoC series.
>
I don't have any objection to this patch. Just that, I could not find
any use-case where we would not like to set the value as MOD_OPCLK_PCLK.
>> The default value for audio playback right now is 00 (2'b), which needs
>> to be fixed anyways.
>
> --
> Regards,
> Sylwester
>
--
Tushar Behera
--
To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
