cafe_ccic slowness in VIDIOC_S_FMT

[Jonathan Corbet]

David Woodhouse <dwmw2 at infradead.org> wrote:

> Do we have a coherent explanation of these problems in the datasheet
> and/or errata? Are they planned to be fixed in a future version of the
> CAFÉ?

I raised the issue with Marvell early on, but didn't get too far.  They
seem to think that it works well enough.

> The majority of the problem in this case is the scheduler -- just
> changing from msleep(2) to mdelay(2) reduces the time taken for ov7670
> init by an order of magnitude (~377 ticks to ~32). 

Interesting.  I'd made a real effort to get the hard delays out of
there, though.  Might the real solution be to use hrtimers here?
There's a *lot* of registers to write, I hate to hog the CPU for 2ms for
every single one of them. 

That said, the hard delays are clearly better than what was there
before.

jon