linux-kernel - Re: [PATCH 0/3] v4.4: Revert "PCI: Implement pcibios_alloc

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Date:	Mon, 18 Apr 2016 09:43:36 -0500
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Joerg Roedel <jroedel@...e.de>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, stable@...r.kernel.org,
	ОлегМороз <oleg.moroz@....vniiem.ru>,
	"Rafael J. Wysocki" <rafael@...nel.org>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Sunjin Yang <fan4326@...il.com>,
	Rob Groner <rgroner@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jiang Liu <jiang.liu@...ux.intel.com>
Subject: Re: [PATCH 0/3] v4.4: Revert "PCI: Implement pcibios_alloc_irq() and

On Mon, Apr 18, 2016 at 01:50:15PM +0200, Joerg Roedel wrote:
> Hi Bjorn,
> 
> On Fri, Apr 15, 2016 at 10:08:21AM -0500, Bjorn Helgaas wrote:
> > I assume you're thinking about doing pci_enable_resources() before
> > the core calls the driver's probe method?  One question there is how
> > we would deal with pci_enable_device_mem().  If the core calls
> > pci_enable_resources(), it has to assume the driver requires all BARs,
> > and there are quite a few drivers that don't need the I/O BARs.
> 
> Yes, I think that the problem might be fixed when the resources are
> enabled during the pcibios-call.
> 
> What do you think of enabling the the resources at probe time for the
> pcibios-call and disable them afterwards? Then the driver can re-enable
> whatever it needs and keep the rest disabled.

That might work, but the problem seems to be that we aren't enabling
IRQs correctly, so I'd rather have a fix that explicitly addresses
IRQs than one that relies on some non-obvious connection between
enabling BARs and IRQs.

Bjorn