linux-kernel - Re: [PATCH] fakephp: Allocate PCI resources before adding the device

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Message-Id: <200812161133.33894.jbarnes@virtuousgeek.org>
Date:	Tue, 16 Dec 2008 11:33:33 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Rolf Eike Beer <eike-kernel@...tec.de>
Cc:	Trent Piepho <xyzzy@...akeasy.org>,
	"Darrick J. Wong" <djwong@...ibm.com>,
	Alex Chiang <achiang@...com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"linux-pci" <linux-pci@...r.kernel.org>
Subject: Re: [PATCH] fakephp: Allocate PCI resources before adding 
 the	device

On Monday, December 1, 2008 9:08 am Rolf Eike Beer wrote:
> Trent Piepho wrote:
> > On Fri, 28 Nov 2008, Rolf Eike Beer wrote:
> > > Trent Piepho wrote:
> > > > On Wed, 26 Nov 2008, Darrick J. Wong wrote:
> > > > > On Wed, Nov 26, 2008 at 03:55:35PM -0700, Alex Chiang wrote:
> > > > > > > Maybe it's different on powerpc then?  My pseudo-hotplugable
> > > > > > > device is also the only thing connected to the PCI-E host bus
> > > > > > > controller. At boot the controller is empty and so I think some
> > > > > > > code to enable its BARs gets skipped.  But without the
> > > > > > > pci_enable_device(), I get this:
> > > > > > >
> > > > > > > 01:00.0 Signal processing controller: Freescale Semiconductor
> > > > > > > Inc Aurora Nexus Trace Interface Flags: fast devsel, IRQ 255
> > > > > > > Memory at 40000000 (64-bit, prefetchable) [disabled] [size=4K]
> > > > >
> > > > >                            Are you referring to this? ^^^^^^^^^^
> > > > >
> > > > > Without seeing the raw dump of the PCI config space, it looks to me
> > > > > like the memory space enable bit of the PCICMD register is unset.
> > > > > Probably the device driver should call pci_enable_device() at init
> > > > > time, though I suppose you did say earlier that there is no driver.
> > > >
> > > > Yes, that's it.  It seems like since the BARs are normally enabled
> > > > after a device is scanned at boot time that they should also be
> > > > enabled when a device is found by a fakephp rescan.  So I thought it
> > > > seemed reasonable to put pci_enable_device() in fakephp.
> > >
> > > No, pci_enable_device() will be called by the device driver. The
> > > hotplug drivers have nothing to do with that.
> >
> > I guess you didn't read the part about there not being a device driver?
>
> I read it, but that's the way a kernel works: if you want to talk to a
> device, get a driver. You can write a rather minimal one that does only
> pci_enable_device() on probe and pci_disable_device() on remove. Try the
> one posted by Chris Wright in "[PATCH 2/2] PCI: pci-stub module to reserve
> pci device" as a starting point.

Ok, so sounds like Darrick's original patch gets a NAK?  I guess the fakephp 
vs. dummyphp vs. new interface stuff can be dealt with in another thread...
-- 
Jesse Barnes, Intel Open Source Technology Center

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