On 3/11/2021 4:46 PM, Michael Walle wrote:
Am 2021-03-11 12:05, schrieb Sameer Pujar:
It would work and initially I had similar patch, see [0] and related
series. Suggestion is to always use "clocks" property with devices
only.
I see. But again, I don't think it is correct to change the clock of
the codec by default. What happens if this is for example a
compatible = "fixed-clock"?
The codec rate won't be changed unless a corresponding "*mclk-fs" is
provided.
As you pointed out in the referred thread [0]. simple-audio-card has
that clock and judging from the code it is exactly for this reason:
to either change/enable it or not.
With this patch you'll switch that to "always change it". Therefore,
shouldn't there be a dt flag to indicate wheter simple-audio-card/graph
should be in charge of the codecs clock input?
As mentioned above, it does not change always. Requires "*mclk-fs" to do so.
May be below could be a possible alternative?
- Re-order if-else of clock parsing.
if (!of_property_read_u32(node, "system-clock-frequency", &val)) {
// Since you are fixing rate already via "assigned-clocks" this
may be a duplication. OR
// "assigned-clocks" can be parsed to understand if a fixed rate
is expected.
simple_dai->sysclk = val;
} else {
// fetch MCLK clock from device and setup sysclk
// a. If "*mclk-fs" is given and "clocks" is found, the rate
would be updated.
// b. If "*mclk-fs" is not mentioned and "clocks" is found, then
simple-card utils won't touch rate. It will just do clock enable/disable.
}
And its fetching just the first clock, doesn't it? What happens if a
codec has two clock inputs?
Yes, it would have been more descriptive if it were specifically looking
for clock "mclk". I think the original assumption was codec takes one
input clock (MCLK) and uses it for sysclk.
-michael
[0]
https://patchwork.kernel.org/project/alsa-devel/patch/1611944866-29373-4-git-send-email-spujar@xxxxxxxxxx/
