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@samsung.com
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