Re: [Regression, post-rc2] Commit a5ee4eb7541 breaks OpenGL on RS780(was: Re: Linux 2.6.34-rc3)

From: Clemens Ladisch
Date: Thu Apr 01 2010 - 02:36:38 EST

Alex Deucher wrote:
> On Wed, Mar 31, 2010 at 9:13 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
>> On Tuesday 30 March 2010, Rafael J. Wysocki wrote:
>>> > PCI quirk: RS780/RS880: work around missing MSI initialization
>>> This one (commit a5ee4eb7541) broke OpenGL acceleration on my new test box
>>> which happens to have a RS780.

So it's better to disable MSI unconditionally.

Rafael, can you check if MSI works for the HDMI audio device?
(I'd guess it doesn't.)

> I also have the attached patch queued in via Dave's tree to disable
> MSI on all IGP chips for the time being.

This disables MSI only for the graphics device. I'd prefer to have
the quirk on its bridge so that MSI gets disabled for the HDMI audio
device too, to avoid having to duplicate this quirk in the snd-hda-intel


PCI quirk: RS780/RS880: disable MSI completely

The missing initialization of the nb_cntl.strap_msi_enable does not seem
to be the only problem that prevents MSI, so that quirk is not
sufficient to enable MSI on all machines. To be safe, unconditionally
disable MSI for the internal graphics and HDMI audio on these chipsets.

Signed-off-by: Clemens Ladisch <clemens@xxxxxxxxxx>

--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2123,6 +2123,8 @@ static void __devinit quirk_disable_msi(struct pci_dev *dev)
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x9602, quirk_disable_msi);
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, 0xa238, quirk_disable_msi);

/* Go through the list of Hypertransport capabilities and
@@ -2495,39 +2497,6 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4374,

- * 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
- rs780_int_gfx_disable_msi);
-/* wrong vendor ID on M4A785TD motherboard: */
- rs780_int_gfx_disable_msi);
#endif /* CONFIG_PCI_MSI */

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