linux-kernel - Re: [Update][PATCH] ACPI / scan: Add a scan handler for PRP0001

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Date:	Sat, 25 Apr 2015 04:25:59 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Darren Hart <dvhart@...radead.org>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Zhang Rui <rui.zhang@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [Update][PATCH] ACPI / scan: Add a scan handler for PRP0001

On Friday, April 24, 2015 03:21:00 PM Darren Hart wrote:
> On Fri, Apr 24, 2015 at 02:15:22AM +0200, Rafael Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > 
> > If the special PRP0001 device ID is present in the given device's list
> > of ACPI/PNP IDs and the device has a valid "compatible" property in
> > the _DSD, it should be enumerated using the default mechanism,
> > unless some scan handlers match the IDs preceding PRP0001 in the
> > device's list of ACPI/PNP IDs.  In addition to that, no scan handlers
> > matching the IDs following PRP0001 in that list should be attached
> > to the device.
> > 
> > To make that happen, define a scan handler that will match PRP0001
> > and trigger the default enumeration for the matching devices if the
> > "compatible" property is present for them.
> > 
> > Since that requires the check for platform_id and device->handler
> > to be removed from acpi_default_enumeration(), move the fallback
> > invocation of acpi_default_enumeration() to acpi_bus_attach()
> > (after it's checked if there's a matching ACPI driver for the
> > device), which is a better place to call it, and do the platform_id
> > check in there too (device->handler is guaranteed to be unset at
> > the point where the function is looking for a matching ACPI driver).
> > 
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Acked-by: Darren Hart <dvhart@...ux.intel.com>
> > ---
> > 
> > The change from the original patch is to change the scan handler
> > behavior to make it return 1 also if the "compatible" property is
> > not present, in which case the additional scan handlers should not
> > trigger too *and* the default enumeration should not trigger either
> > (as there's no ID to match to), which will allow things like
> > auxiliary nodes (think GPIO buttons/LEDs etc) to be easily represented.
> 
> 
> This should probably be spelled out in the commit message itself as it's a fairly
> unique condition.

I'm going to document that in Documentation/acpi/enumeration.txt anyway.

> > Darren, I've tentatively added your Acked-by tag to this one, please
> > let me know if that's not appropriate.
> 
> Spent a bit more time on it this time, so:
> 
> Reviewed-by: Darren Hart <dvhart@...ux.intel.com>

Thanks!

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