Re: [PATCH v2 1/2] drm/bridge/synopsys: dw-hdmi: Handle audio for more clock rates

From: Doug Anderson
Date: Wed Jun 26 2019 - 15:30:30 EST


Hi,

On Wed, Jun 26, 2019 at 2:56 AM Andrzej Hajda <a.hajda@xxxxxxxxxxx> wrote:
>
> > AKA: anyone using auto-CTS won't notice any change
> > at all. I guess the question is: with Auto-CTS should you pick the
> > "ideal" 6272 or a value that allows CTS to be the closest to integral
> > as possible. By reading between the lines of the spec, I decided that
> > it was slightly more important to allow for an integral CTS. If
> > achieving an integral CTS wasn't a goal then the spec wouldn't even
> > have listed special cases for any of the clock rates. We would just
> > be using the ideal N and Auto-CTS and be done with it. The whole
> > point of the tables they list is to make CTS integral.
>
>
> Specification recommends many contradictory things without explicit
> prioritization, at least I have not found it.
>
> So we should relay on our intuition.
>
> I guess that with auto-cts N we should follow recommendation - I guess
> most sinks have been better tested with recommended values.
>
> So what with non-auto-cts case:
>
> 1. How many devices do not have auto-cts? how many alternative TMDS
> clocks we have? Maybe it is theoretical problem.
>
> 2. Alternating CTS in software is possible, but quite
> complicated/annoying, but at least it will follow recommendation :)

It is OK w/ me if we want to drop my patch. With the auto-CTS patch
it shouldn't matter anymore. ...but I still wanted to post it to the
list for posterity in case it is ever useful for someone else.

-Doug