Re: [PATCH] mmc: support sdhci-mmp2

Arnd Bergmann
2011-05-28T19:04:44Z

On Saturday 28 May 2011 18:25:00 Philip Rakity wrote:
> On May 28, 2011, at 1:52 AM, Arnd Bergmann wrote:
> > I would actually prefer in general if the Kconfig file listed only
> > the strictly necessary dependencies for building the driver.
> > If this driver can be built anywhere, I would list no dependency at
> > all. If it depends on something ARM specific, I'd make it depend
> > on CONFIG_ARM.
> >
> > Then change the defconfig for the particular board to enable the
> > driver.
> >
> > The main advantage of this is to increase build coverage on test
> > building machines doing an allyesconfig and randconfig once we
> > get there (right now, these have too many build errors, but we
> > have plans to work on that).
>
> The controller is built into the mmp2 SoC. No build error could
> occur if once the SoC is determined it selected the type of
> controller available (in the arch/arm). Like the patch you
> helped me with a while ago (which never was accepted).

My point was not avoiding build errors in this driver, which is
fairly easy and obviously needs to happen. I want to enable the
driver (and most others) to be built in all cases that don't
cause a build error, instead of limiting them to very few
configurations.

> The Kconfig entry for MMP2 in drivers/mmc/host would
> add the line
> depends on
>
> This is not a general as depending on ARM but at least
> the code would work.
>
> The best solution would be far more general and involve
> generic probing and registration but that is a lot of work and
> should be done for all of the arm/ directory.

We actually do all the generic probing based on the machine
type already. Any place where we don't do that and hardcode
the presence of a device based on a compile-time option should
be considered a bug.

> > I guess the idea was to be able to free the structure later. I already
> > commented that it should be statically allocation instead of kzalloc,
> > so that would make the pointer unnecessary.
>
> I do not understand why pxa->ops is needed at all. More general
> question.

pxa->ops is the same as host->ops, which is required by the base
sdhci driver.

Arnd