Hello Mark and Emanuele
On Wed, Dec 07, 2022 at 05:37:50PM +0000, Mark Brown wrote:
On Wed, Dec 07, 2022 at 01:41:24PM +0100, Emanuele Ghidoli wrote:
I guess what is the "right/better" implementation? Have we to add the set_pll call in simple-card? Or have we to add it to e.g. fsl_sai driver? Or, in some way, the wm8904 codec driver is approaching in the right way?
Is there any documentation that explain all of that (I have already looked at Documentation/sound)? Any driver that is considered well written and complete I should use as a reference?
It's kind of a taste thing. There's some devices where the clocking is sufficently complicated and flexible that definitely needs a set_pll() ... for simpler devices like the WM8904 where there's an obvious thing to do it's much easier to just hide that from everything outside the driver and only deal with the input clock.
Thinking about asoc_simple_hw_params(), what about the fact that asoc_simple_set_clk_rate() ask for a specific clock rate and assume that the actual output frequency is the one requested?
After that we are potentially passing to the codec driver a wrong information, we should likely have a way to pass the actual clock that could be different because of limitation on the PLL/dividers.
Francesco