• Mikel Rychliski's avatar
    PCI: Add AMD RS690 quirk to enable 64-bit DMA · cacf994a
    Mikel Rychliski authored
    Although the AMD RS690 chipset has 64-bit DMA support, BIOS implementations
    sometimes fail to configure the memory limit registers correctly.
    
    The Acer F690GVM mainboard uses this chipset and a Marvell 88E8056 NIC. The
    sky2 driver programs the NIC to use 64-bit DMA, which will not work:
    
      sky2 0000:02:00.0: error interrupt status=0x8
      sky2 0000:02:00.0 eth0: tx timeout
      sky2 0000:02:00.0 eth0: transmit ring 0 .. 22 report=0 done=0
    
    Other drivers required by this mainboard either don't support 64-bit DMA,
    or have it disabled using driver specific quirks. For example, the ahci
    driver has quirks to enable or disable 64-bit DMA depending on the BIOS
    version (see ahci_sb600_enable_64bit() in ahci.c). This ahci quirk matches
    against the SB600 SATA controller, but the real issue is almost certainly
    with the RS690 PCI host that it was commonly attached to.
    
    To avoid this issue in all drivers with 64-bit DMA support, fix the
    configuration of the PCI host. If the kernel is aware of physical memory
    above 4GB, but the BIOS never configured the PCI host with this
    information, update the registers with our values.
    
    [bhelgaas: drop PCI_DEVICE_ID_ATI_RS690 definition]
    Link: https://lore.kernel.org/r/20210611214823.4898-1-mikel@mikelr.comSigned-off-by: default avatarMikel Rychliski <mikel@mikelr.com>
    Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
    cacf994a
fixup.c 27.4 KB