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);
> 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.
> The default value for audio playback right now is 00 (2'b), which needs
> to be fixed anyways.
--
Regards,
Sylwester
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