lkml.org 
[lkml]   [2021]   [Mar]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock
From
Date


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@nvidia.com/
>

\
 
 \ /
  Last update: 2021-03-11 15:31    [W:2.262 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site