linux-kernel - Re: [PATCH] pci: do not try to assign irq 255

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Date:	Tue, 19 Feb 2013 23:36:22 +0100
From:	Frederik Himpe <fhimpe@....ac.be>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Hannes Reinecke <hare@...e.de>, linux-kernel@...r.kernel.org,
	Oliver Neukum <oneukum@...e.de>,
	David Haerdeman <david@...deman.nu>, linux-usb@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH] pci: do not try to assign irq 255

On Tue, Feb 19, 2013 at 12:47:32PM -0700, Bjorn Helgaas wrote:
> On Mon, Feb 18, 2013 at 3:09 AM, Hannes Reinecke <hare@...e.de> wrote:
> > The PCI config space reseves a byte for the interrupt line,
> > so irq 255 actually refers to 'not set'.
> > However, the 'irq' field for struct pci_dev is an integer,
> > so the original meaning is lost, causing the system to
> > assign an interrupt '255', which fails.
> >
> > So we should _not_ assign an interrupt value here, and
> > allow upper layers to fixup things.
> >
> > This patch make PCI devices with MSI interrupts only
> > (like the xhci device on certain HP laptops) work properly.
> >
> > Cc: Frederik Himpe <fhimpe@....ac.be>
> > Cc: Oliver Neukum <oneukum@...e.de>
> > Cc: David Haerdeman <david@...deman.nu>
> > Cc: linux-usb@...r.kernel.org
> > Cc: linux-pci@...r.kernel.org
> > Signed-off-by: Hannes Reinecke <hare@...e.de>
> >
> > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > index 6186f03..a2db887f 100644
> > --- a/drivers/pci/probe.c
> > +++ b/drivers/pci/probe.c
> > @@ -923,7 +923,8 @@ static void pci_read_irq(struct pci_dev *dev)
> >         dev->pin = irq;
> >         if (irq)
> >                 pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq);
> > -       dev->irq = irq;
> > +       if (irq < 255)
> > +               dev->irq = irq;
> >  }
> >
> >  void set_pcie_port_type(struct pci_dev *pdev)
> 
> Is there a bugzilla or other URL with more information (problem
> description, hardware involved, dmesg logs, acpidump, etc)?

https://bugzilla.kernel.org/show_bug.cgi?id=52591
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1072918

Basically it looks like most HP Probook/Elitebook of the Ivy Bridge
generation are affected.

-- 
Frederik Himpe
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