From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Garzik <jeff@garzik.org>
Subject: Re: PCI: Add ALI M5229 comaptibility mode quirk
Date: Sat, 13 Sep 2008 10:24:29 -0400
Message-ID: <48CBCD1D.4090300@garzik.org>
References: <20080912112252.505651015@fluff.org.uk>
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Sender: linux-pci-owner@vger.kernel.org
To: Ben Dooks <ben-linux@fluff.org>
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Linux IDE mailing list <linux-ide@vger.kernel.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>
List-Id: linux-ide@vger.kernel.org

Ben Dooks wrote:
> The libata driver will not work with an M5229 set into native IDE
> mode (the old drivers/pci one does) if the M5229 does not provide
> it's own IRQ.
> 
> The M5229 implementation embedded into the ALI M1543 uses the
> M1543's ISA PIC to provide the interrupts and thus does not have
> an valid PCI IRQ set. This quirk detects the abscence of IRQ and
> sets the M5229 back into compatibility mode to use IRQs 14 and 15
> so that libata works correctly.
> 
> Note, I belive that the check for an valid interrupt line is
> correct, I only have an M5229 in an ALI M1543 to check this
> on. It would be useful to confirm that a M5229 with an valid IRQ
> does not trigger this quirk.
> 
> Signed-off-by: Ben Dooks <ben-linux@fluff.org>
> 
> Index: linux-2.6.27-rc6-cats1/drivers/pci/quirks.c
> ===================================================================
> --- linux-2.6.27-rc6-cats1.orig/drivers/pci/quirks.c	2008-09-11 11:26:35.000000000 +0100
> +++ linux-2.6.27-rc6-cats1/drivers/pci/quirks.c	2008-09-12 12:18:05.000000000 +0100
> @@ -905,6 +905,34 @@ static void __devinit quirk_svwks_csb5id
>  }
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_CSB5IDE, quirk_svwks_csb5ide);
>  
> +/* Some systems set the ALI M5229 in the ALI M1543 bridge to native mode,
> + * which cannot be supported by the pata_ali.c driver (the old drivers/ide
> + * makes a compatibility effort to change the IDE interrupts).
> + */
> +static void __devinit quirk_ali_ide_compatibility(struct pci_dev *pdev)
> +{
> +	u8 tmp;
> +
> +	/* pdev->irq and pdev->pin have yet to be initialised, so check
> +	 * by reading from the configuration header to see if we've got
> +	 * a valid interrupt line. */
> +
> +	pci_read_config_byte(pdev, PCI_INTERRUPT_LINE, &tmp);
> +	if (tmp != 0xff)
> +		return;
> +
> +	pci_read_config_byte(pdev, PCI_CLASS_PROG, &tmp);
> +	if (tmp & 0x5) {
> +		dev_info(&pdev->dev, "quirk: changing to IDE compatibility mode\n");
> +
> +		tmp &= ~0x05;
> +		pdev->class &= ~0x05;
> +		pci_write_config_byte(pdev, PCI_CLASS_PROG, tmp);
> +	}
> +}
> +
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M5229, quirk_ali_ide_compatibility);


This is a bit surprising, considering that libata works for all IDE mode 
of other controllers...

	Jeff