Re: OMAP4 DSS clock setup

Tomi Valkeinen
2011-04-11T09:05:06Z

On Fri, 2011-04-08 at 08:55 -0600, Paul Walmsley wrote:
> Hi
>
> On Fri, 8 Apr 2011, Tomi Valkeinen wrote:

> > and not the clock used for the pixel clock? If so, I'm fine with having
> > "fck" to be what it is currently, but then we need a new name for the
> > clock used for pixel clock, which is consistent on all platforms.
>
> If there is a separate PRCM-provided clock used only for the pixel clock,
> then that clock should have an alias name of "system_pixel_ck" or
> something similar that is meaningful to the DSS driver. I think the
> problem in this case is that "dss_dss_clk" is (optionally) used for two
> purposes: optionally as a "main PRCM-provided functional clock" and
> optionally as a system-provided pixel clock.

Not only for pixel clock, but in the end it'll come out as pixel clock.
I'm not sure what exactly is a "functional clock" here. I mean, one
could think it as a basic functionality of DSS to read the pixels,
manipulate them, and output them (with the rate of the pixel clock).

However, I think there is one difference between the clock used just to
enable the DSS registers, and the one used to output pixels: we need to
be able to adjust the rate of the clock. Thus we need to have a common
(omap2/3/4) clock name for it to be able to clk_get() it.

Should that clock name be just the "main" clock provided automatically,
or something else?

Tomi