Re: [PATCH 0/4] OMAP4: DSS2: Adding fclk support for DPI interface

Raghuveer Murthy
2011-02-16T09:02:02Z

On Monday 14 February 2011 09:32 PM, Valkeinen, Tomi wrote:
> Hi,
>
> On Thu, 2011-02-03 at 07:56 -0600, Murthy, Raghuveer wrote:
>> - Adding dss_feature for DPLL fclk
>> - Enabling pixel clock generation for DPI interface
>
> A bit more description what the patch set is about would be nice. Also,
> one line patch descriptions are a bit too short for anything else than
> the most trivial patches.
>
> Now to the actual patch contents:
>
> DPLL is not a feature of the DSS, and I don't think we should have
> dss_features for that. In fact, I think the whole DPLL code should be
> moved from DSS to somewhere under arch/arm.
>
> In a perfect world DSS could just set the dss_fck to whatever rate it
> requires, but as the clock rate can only be set to certain rates, and we
> need a precise control for the rate, some other method has to be in
> place.
>
> I am not sure what this method should be. Perhaps there is something in
> the clock framework that could help us here, or perhaps we just need a
> bunch of function pointers in the DSS's platform data which can be used
> to configure the clock.
>
> Tomi
>
>

Hi Paul, Benoit,

DPLL_PER post divider output for DSS core functional clock can be
changed in OMAP3xxx and OMAP4430, based on the requested pixel clock for
a given display resolution.

Additionally, the number of dividers available for DPLL_PER post
dividors for DSS has increased from 16 to 32, from OMAP3630 onwards.

Both these are added as dss_features.

Given the above comments from Tomi, can the same be included as part of
the clock framework?

Regards,
Raghuveer