Hi Arnd,

On Wednesday, June 18, 2014 Arnd wrote:

To: Tomasz Figa
Cc: linux-arm-kernel at lists.infradead.org; mark.brown at linaro.org; Tomasz

Figa;

linux-samsung-soc at vger.kernel.org; Kukjin Kim; Russell King - ARM Linux;

Samuel

Ortiz; Pankaj Dubey; linux-kernel at vger.kernel.org; joshi at samsung.com;
vikas.sajjan at samsung.com; chow.kim at samsung.com; Lee Jones
Subject: Re: [PATCH RFC] mfd: syscon: Decouple syscon interface from

syscon

devices

On Tuesday 17 June 2014 23:26:22 Tomasz Figa wrote:

quoted

On 17.06.2014 17:42, Arnd Bergmann wrote:

quoted

This seems like a reasonable way of solving the problem, but I think
there is an even better one that we have about in the past: if we
promote syscon from a platform driver into a a drivers/base/ helper
that is independent of the platform device matching, we can use call
syscon_regmap_lookup_* for any device node, whether it's already
bound to a driver or not, which do what you need. It would also make
it easier to call the syscon code before the platform_device
infrastructure gets initialized, which is something a number of
people have asked for, e.g. for using regmap to do SMP bringup or
for clock registration.

Basically, unless I'm missing your point, this is what my patch does,
except that I don't move it to drivers/base/ and the registration
function I added require a pointer to struct device. Indeed,
decoupling it further from the driver model, by adding
of_syscon_register() should be useful for early users.

I believe the part you are missing is that with the approach I suggested,

there would

be no registration function at all. You can easily do the lookup from the

client drivers

using the DT data structures, with no need for the device at all. 

Will you please elaborate more on this? 

The only exception

today is the clps711x platform using syscon_regmap_lookup_by_pdevname(),

but

that should be solved in 3.17 when clps711x becomes DT-only.

Does it mean that this may become a blocking issue for this patch to go
before 3.17?
If yes, isn't it will be good to accept this patch as it is if it's not
causing issue or breaking
anything with existing users of syscon. At least for our use of converting
Exynos PMU and
PM related consolidation this change is working fine and we have verified
it.

quoted

Should I move this to drivers/base/, even though from current location
it can be used outside the platform driver anyway?

Thinking about it some more, drivers/of might be better than drivers/base.
It depends a bit where we are heading with this, in particular if we

expect to see non-

DT users in the future.

	Arnd

Thanks,
Pankaj Dubey