Re: MMC: Make the configuration memory resource optional

Magnus Damm
2009-07-29T12:51:31Z

On Wed, Jul 29, 2009 at 9:42 PM, Mark
Brown<broonie@opensource.wolfsonmicro.com> wrote:
> On Wed, Jul 29, 2009 at 09:27:54PM +0900, Magnus Damm wrote:
>> On Wed, Jul 29, 2009 at 8:58 PM, Mark
>> Brown<broonie@opensource.wolfsonmicro.com> wrote:
>
>> > While it's true that this doesn't bother SoCs the fact that most clock
>> > API implementations don't allow any off-chip drivers to register clocks
>> > renders the clock API essentially unusable for fairly large parts of the
>
>> Yeah, clocks outside the SoC are not well supported today. From what
>> I've seen, most embedded boards come with external chips for cameras,
>> audio codecs and/or phy devices. These devices often get their clocks
>> from the main SoC. Allowing the drivers for such chips to use the
>> clock framework to register clocks for internal divisors would allow
>> driver writers to write better code which in turn would make life
>> easier for most people hacking on embedded kernels.
>
> That's not actually abundantly clear for the audio stuff, or rather the
> audio stuff would like additional features like constraint based
> configuration.

Without knowing too much about this, wouldn't camera sensors want
similar features?

>> The problem with the clock framework API is that the data structures
>> varies depending on implementation. So the ops callback structure on
>> SuperH is different compared to ARM. I suspect that adding generic
>> clocklib support across the architectures will take quite a bit of
>> time to implement propely.
>
> Indeed.  It's actually much worse than you say, each individual ARM
> architecture has its own clock API implementation of varying quality and
> of course there are architectures that don't do the clock API at all.

Yeah. This is exactly why I don't want to block on the clocklib implementation.

Cheers,

/ magnus