Re: [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts

[Adam Ford]

On Mon, Sep 30, 2019 at 9:27 AM Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote:
>
> On 30/09/2019 17:20, Tomi Valkeinen wrote:
>
> > Let's see what Tero says, but yeah, something is odd here. I expected
> > the max divider to be 16 with Tero's patch, but I don't see it having
> > that effect. I can get the div to 31.
> >
> > You can see this from the clock register 0x48004e40 (CM_CLKSEL_DSS). The
> > lowest bits are the divider, 5 to 0. The TRM says max div is 32.
> >
> > Tero said for him the dividers > 16 didn't "stick" to the register. I'm
> > now wondering if he has an old beagleboard with OMAP34xx, which has max
> > div 16.
>
> So testing a bit more here, I can see the DSS working fine and fps as
> expected when I write values directly to CM_CLKSEL_DSS:5:0, with
> dividers up to 31. With 32, DSS breaks. The TRM (AM/DM37x) says value 32
> is valid.

I wonder if it's somehow being masked with bits 4:0 instead of 5:0
which could potentially make the divider 0 and that value doesn't
appear to be valid.

adam

>
>   Tomi
>
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