linux-kernel - Re: [Resend][PATCH] ACPI / glue: Drop .find_bridge() callback from struct acpi_bus

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Date:	Thu, 28 Feb 2013 02:19:04 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lan Tianyu <tianyu.lan@...el.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-usb@...r.kernel.org,
	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	Jeff Garzik <jgarzik@...ox.com>
Subject: Re: [Resend][PATCH] ACPI / glue: Drop .find_bridge() callback from struct acpi_bus_type

On Wednesday, February 27, 2013 03:31:08 PM Yinghai Lu wrote:
> On Wed, Feb 27, 2013 at 2:20 PM, Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> > On Wed, Feb 27, 2013 at 11:06:52PM +0100, Rafael J. Wysocki wrote:
> >> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>
> >> After PCI has stopped using the .find_bridge() callback in
> >> struct acpi_bus_type, the only remaining users of it are SATA and
> >> USB.  However, SATA only pretends to be a user, because it points
> >> that callback to a stub always returning -ENODEV, and USB uses it
> >> incorrectly, because as a result of the way it is used by USB every
> >> device in the system that doesn't have a bus type or parent is
> >> passed to usb_acpi_find_device() for inspection.
> >>
> >> What USB actually needs, though, is to call usb_acpi_find_device()
> >> for USB ports that don't have a bus type defined, but have
> >> usb_port_device_type as their device type.
> >
> > Ick, that's not good.  Can you have the original creator of that code
> > (someone else from Intel, I can't remember at the moment), fix that up
> > properly and send me patches?
> 
> [Add To: Lan Tianyu <tianyu.lan@...el.com>]
> 
> >
> >> Please let me know if there are any objections.
> 
> I still prefer to ask USB to add bus_type instead at first.

IIRC, You want USB to register an *additional* ACPI bus type for
usb_port_device_type, which quite frankly will be very confusing and I don't
see any actual benefits from doing that.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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