linux-kernel - Re: [PATCH 2/3] spi / ACPI: add ACPI enumeration support

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Message-ID: <20121108202042.GD16012@intel.com>
Date:	Thu, 8 Nov 2012 22:20:42 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, linux-kernel@...r.kernel.org,
	lenb@...nel.org, rafael.j.wysocki@...el.com,
	broonie@...nsource.wolfsonmicro.com, grant.likely@...retlab.ca,
	linus.walleij@...aro.org, khali@...ux-fr.org, ben-linux@...ff.org,
	w.sang@...gutronix.de, mathias.nyman@...ux.intel.com,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH 2/3] spi / ACPI: add ACPI enumeration support

On Thu, Nov 08, 2012 at 01:46:24AM +0100, Rafael J. Wysocki wrote:
> On Wednesday, November 07, 2012 03:05:48 PM Mika Westerberg wrote:
> > On Wed, Nov 07, 2012 at 12:14:31PM +0100, Rafael J. Wysocki wrote:
> > > > So is the idea now that the ACPI core parses the resources and passes them
> > > > forward via struct acpi_device? I'm just wondering how to proceed with
> > > > these I2C and SPI enumeration patches.
> > > 
> > > Well, we definitely don't want to duplicate what drivers/pnp/pnpacpi/rsparser.c
> > > does, so the idea is to move the code from there to the core in such a way that
> > > both the SPI/I2C patches and the PNP layer can use it.
> > 
> > Ok.
> > 
> > > I'll have some prototype code ready shortly, hopefully, and I'll post it
> > > in that form for comments (and so that you know what to expect).
> > 
> > Sounds good. Thanks!
> 
> There you go.
> 
> I haven't even try to compile it, so most likely it breaks things left, right
> and in between, but I hope it shows the idea.

Thanks Rafael!

I'll try this tomorrow (we had problems with the HW today so I wasn't able
to do any testing).

I'll convert the SPI and I2C enumeration patches to use this method.

> It does a couple of things at the same time, so it should be split into a few
> simpler patches.  First, it moves some code from drivers/pnp/pnpacpi/rsparser.c
> to a new file drivers/acpi/resource.c and makes pnpacpi use functions from
> there.  Second, it changes acpi_platform.c to use those functions too.
> Finally, it adds a list of ACPI resources to struct acpi_device and
> makes acpi_platform.c use that list intead of evaluating _CRS and parsing its
> output with acpi_walk_resources().
> 
> While changing acpi_platform.c I noticed that we had a bug in there, because
> GSIs were registered for the struct acpi_device object, although they should be
> registered for the struct platform_device one created by that code.  I didn't
> try to fix that in the patch below, but it generally needs fixing.

Good point.

I wonder if the acpi_register_gsi() wants a device that is registered to
the Linux device framework? At least with the SPI and I2C we generally
don't have such until we call i2c_new_device() or spi_add_device() and they
are getting passed the IRQ number which should be translated to the Linux
IRQ before that...
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