On Mon, Aug 03, 2015 at 08:09:35PM +0100, Russell King - ARM Linux wrote:

On Mon, Aug 03, 2015 at 09:26:23AM -0700, Greg Kroah-Hartman wrote:

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On Mon, Aug 03, 2015 at 10:49:23AM +0100, Russell King - ARM Linux wrote:

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On Mon, Aug 03, 2015 at 05:26:05PM +0800, Shannon Zhao wrote:

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Hi Russell,

On 2015/8/3 15:58, Russell King - ARM Linux wrote:

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On Mon, Aug 03, 2015 at 02:59:56PM +0800, Shannon Zhao wrote:

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From: Shannon Zhao <redacted>

According to ACPI SPEC, it supports ARM boards to use "GPIO-signaled
ACPI Events". These events can be used for input events. And to QEMU, it
uses GPIO PL061 controller for input events.

These two patches add platform driver support for PL061 probed by DT or
ACPI.

This certainly is incorrect for DT, and is probably wrong for ACPI too.
DT creates amba devices, so binds via the amba device driver.

Oh, sorry. The changes for DT are not necessary. But for ACPI I think it
needs to convert pl061 to platform device since ACPI doesn't support
AMBA devices. The Pl011 also does the same thing to support ACPI
probing. See drivers/tty/serial/amba-pl011.c

Maybe rather than having every AMBA driver also converted to a platform
driver (which GregKH hates) maybe ACPI should support the AMBA bus
instead?

Greg?

The ACPI developers have been doing work to allow a driver to handle
getting the resources from either DT or ACPI no matter what bus it is
on, so converting anything to a platform driver shouldn't be needed.

but I don't really know the details here, and this isn't being sent to
the ACPI mailing list, so I don't know what to suggest...

Greg,

You're the one who's said many times that you'd like to see platform
devices and platform device drivers to go away.

Yes, of course, I hate the things :)

So, when I give you
the opportunity to comment on platform devices being used to augment
existing device drivers such as the AMBA bus drivers (which you've
also previously said is a more preferable way to use the driver model)
why not support that view?

Because I don't know the whole story here, sorry.

Right now, there seems to be a move to convert _all_ AMBA device drivers
to become dual-drivers: an amba bus driver and a platform driver.  Is
that something you really want to see, irrespective of ACPI issues?

Ick, no, I don't think that's wise at all.  Why not just make the needed
resources availble to _all_ bus drivers, then it doesn't matter if it's
AMBA, or ACPI, or USB, or anything else?

I thought that is what some recent patches did to the acpi/of core, but
maybe I was mistaken.

thanks,

greg k-h