linux-kernel - Re: [PATCH] pci: Add quirk for still enabled interrupts on Intel Sandy Bridge GPUs

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Date:	Wed, 7 Dec 2011 13:30:00 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Thomas Jarosch <thomas.jarosch@...ra2net.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Charlie Suffin <charlie.suffin@...atus.com>, stable@...nel.org
Subject: Re: [PATCH] pci: Add quirk for still enabled interrupts on Intel
 Sandy Bridge GPUs

On Wed, 07 Dec 2011 22:08:11 +0100
Thomas Jarosch <thomas.jarosch@...ra2net.com> wrote:
> +#define I915_DEIER_REG 0x4400c
> +static void __devinit disable_igfx_irq(struct pci_dev *dev)
> +{
> +	void __iomem *regs = pci_iomap(dev, 0, 0);
> +	if (regs == NULL) {
> +		dev_warn(&dev->dev, "igfx quirk: Can't iomap PCI device\n");
> +		return;
> +	}
> +
> +	/* Check if any interrupt line is still enabled */
> +	if (readl(regs + I915_DEIER_REG) != 0) {
> +		dev_warn(&dev->dev, "BIOS left Intel GPU interrupts enabled; "
> +			"disabling\n");
> +
> +		writel(0, regs + I915_DEIER_REG);
> +	}
> +
> +	pci_iounmap(dev, regs);
> +}
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x0102, disable_igfx_irq);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x010a, disable_igfx_irq);
> +
>  static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
>  			  struct pci_fixup *end)
>  {

Could really be dev_dbg, I think this will be fairly common.  I think we
also need to ack any outstanding interrupts after disabling them in IER
by writing IIR back on itself. Can you test that?

-- 
Jesse Barnes, Intel Open Source Technology Center

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