linux-kernel - Re: [091/156] PCI quirk: RS780/RS880: work around missing MSI initialization

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Date:	Wed, 31 Mar 2010 22:40:39 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Clemens Ladisch <clemens@...isch.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [091/156] PCI quirk: RS780/RS880: work around missing MSI initialization

On Wednesday 31 March 2010, Greg KH wrote:
> 2.6.33-stable review patch.  If anyone has any objections, please let us know.

I do, this one causes a regression to happen on my test box.

Rafael


> ------------------
> 
> From: Clemens Ladisch <clemens@...isch.de>
> 
> commit a5ee4eb75413c145334c30e43f1af9875dad6fd7 upstream.
> 
> AMD says in section 2.5.4 (GFX MSI Enable) of #43291 (AMD 780G Family
> Register Programming Requirements):
> 
>   The SBIOS must enable internal graphics MSI capability in GCCFG by
>   setting the following: NBCFG.NB_CNTL.STRAP_MSI_ENABLE='1'
> 
> Quite a few BIOS writers misinterpret this sentence and think that
> enabling MSI is an optional feature.  However, clearing that bit just
> prevents delivery of MSI messages but does not remove the MSI PCI
> capabilities registers, and so leaves these devices unusable for any
> driver that attempts to use MSI.
> 
> Setting that bit is not possible after the BIOS has locked down the
> configuration registers, so we have to manually disable MSI for the
> affected devices.
> 
> This fixes the codec communication errors in the HDA driver when
> accessing the HDMI audio device, and allows us to get rid of the
> overcautious quirk in radeon_irq_kms.c.
> 
> Signed-off-by: Clemens Ladisch <clemens@...isch.de>
> Tested-by: Alex Deucher <alexdeucher@...il.com>
> Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  drivers/gpu/drm/radeon/radeon_irq_kms.c |    8 -------
>  drivers/pci/quirks.c                    |   33 ++++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 7 deletions(-)
> 
> --- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
> +++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
> @@ -116,13 +116,7 @@ int radeon_irq_kms_init(struct radeon_de
>  	}
>  	/* enable msi */
>  	rdev->msi_enabled = 0;
> -	/* MSIs don't seem to work on my rs780;
> -	 * not sure about rs880 or other rs780s.
> -	 * Needs more investigation.
> -	 */
> -	if ((rdev->family >= CHIP_RV380) &&
> -	    (rdev->family != CHIP_RS780) &&
> -	    (rdev->family != CHIP_RS880)) {
> +	if (rdev->family >= CHIP_RV380) {
>  		int ret = pci_enable_msi(rdev->pdev);
>  		if (!ret) {
>  			rdev->msi_enabled = 1;
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2484,6 +2484,39 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AT
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4375,
>  			quirk_msi_intx_disable_bug);
>  
> +/*
> + * MSI does not work with the AMD RS780/RS880 internal graphics and HDMI audio
> + * devices unless the BIOS has initialized the nb_cntl.strap_msi_enable bit.
> + */
> +static void __init rs780_int_gfx_disable_msi(struct pci_dev *int_gfx_bridge)
> +{
> +	u32 nb_cntl;
> +
> +	if (!int_gfx_bridge->subordinate)
> +		return;
> +
> +	pci_bus_write_config_dword(int_gfx_bridge->bus, PCI_DEVFN(0, 0),
> +				   0x60, 0);
> +	pci_bus_read_config_dword(int_gfx_bridge->bus, PCI_DEVFN(0, 0),
> +				  0x64, &nb_cntl);
> +
> +	if (!(nb_cntl & BIT(10))) {
> +		dev_warn(&int_gfx_bridge->dev,
> +			 FW_WARN "RS780: MSI for internal graphics disabled\n");
> +		int_gfx_bridge->subordinate->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
> +	}
> +}
> +
> +#define PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX	0x9602
> +
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD,
> +			PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX,
> +			rs780_int_gfx_disable_msi);
> +/* wrong vendor ID on M4A785TD motherboard: */
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ASUSTEK,
> +			PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX,
> +			rs780_int_gfx_disable_msi);
> +
>  #endif /* CONFIG_PCI_MSI */
>  
>  #ifdef CONFIG_PCI_IOV
> 
> 
> --
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