Re: [PATCH 04/10] media: ar0521: Rework PLL computation

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Hi Laurent,

On Fri, Oct 07, 2022 at 04:56:01PM +0300, Laurent Pinchart wrote:
> Hi Jacopo,
> 
> Thank you for the patch.
> 
> On Wed, Oct 05, 2022 at 09:06:07PM +0200, Jacopo Mondi wrote:
> > Rework the PLL computation procedure to take into account the currently
> > configured format bpp and the number of data lanes.
> > 
> > Comment the PLL configuration procedure with information provided by the
> > sensor chip manual and remove the hardcoded divider from the pixel clock
> > calculation.
> > 
> > The PLL configuration procedure has been verified by forcing a pixel
> > rate of 414 MHz and verify that the effective output pixel rate matches
> > the expected 60 frames per second.
> 
> This is the kind of code that would benefit from testing with kunit.
> 
> > Do not modify the default pixel rate for the moment as it will be made
> > configurable through V4L2_CID_LINK_FREQ in subsequent patches.
> > 
> > Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
> 
> I think we should extract the PLL calculation code from the CCS driver
> into a library. Sakari ? :-)

It already is a module. I think there is another driver using it, written
by you. :-)

Some PLLs are as in CCS but there are different ones, too, especially in
Omnivision sensors. Sometimes CCS PLL calculator can be used on non-CCS sensors
by fixing one of the multipliers or divisors to 1.

-- 
Sakari Ailus



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