Hi Daniel,
On Mon, Jun 19, 2017 at 12:35:28PM +1000, Daniel Axtens wrote:
> The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) that
> are not spec-compliant: they do not set the VGA Enable bit when a VGA
> card is behind the bridge. This breaks Xorg auto-detection.
I don't understand what is not spec-compliant about this. The VGA
Enable bit (PCI_BRIDGE_CTL_VGA) is a read/write bit, and the bridge
itself is not responsible for figuring out whether it has a VGA card
below it.
Some software (firmware/OS/etc) that enumerates the hierarchy is
responsible for setting PCI_BRIDGE_CTL_VGA if desired.
> Despite this, the hibmc VGA card (PCI ID 19e5:1711) is known to work
> when behind these bridges.
>
> Provide a quirk so that this combination of bridge and card is eligible
> to be the default VGA card.
>
> This fixes Xorg auto-detection.
>
> Cc: Xinliang Liu <z.liuxinliang@xxxxxxxxxxxxx>
> Cc: Rongrong Zou <zourongrong@xxxxxxxxx>
> Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
> ---
> drivers/pci/quirks.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 46 insertions(+)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 16e6cd86ad71..9475d6056dd3 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -25,6 +25,7 @@
> #include <linux/sched.h>
> #include <linux/ktime.h>
> #include <linux/mm.h>
> +#include <linux/vgaarb.h>
> #include <asm/dma.h> /* isa_dma_bridge_buggy */
> #include "pci.h"
>
> @@ -4664,3 +4665,48 @@ static void quirk_intel_no_flr(struct pci_dev *dev)
> }
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr);
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr);
> +
> +/*
> + * The hibmc card on a HiSilicon D05 board sits behind a non-compliant
> + * bridge. The bridge doesn't advertise the PCI_BRIDGE_CTL_VGA bit in
> + * its config space. This prevents the vgaarb from marking a card
> + * behind it as boot VGA device.
> + *
> + * However, the hibmc card is known to still work, so if we have that
> + * card behind that particular bridge (19e5:1610), mark it as the
> + * default device if none has been detected.
> + */
> +static void hibmc_fixup_vgaarb(struct pci_dev *pdev)
> +{
> + struct pci_dev *bridge;
> + struct pci_bus *bus;
> + u16 config;
> +
> + bus = pdev->bus;
> + bridge = bus->self;
> + if (!bridge)
> + return;
> +
> + if (!pci_is_bridge(bridge))
> + return;
> +
> + if (bridge->vendor != PCI_VENDOR_ID_HUAWEI ||
> + bridge->device != 0x1610)
> + return;
> +
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &config);
> + if (config & PCI_BRIDGE_CTL_VGA) {
> + /*
> + * Weirdly, this bridge *is* spec compliant, so bail
> + * and let vgaarb do its job
> + */
> + return;
> + }
> +
> + if (vga_default_device())
> + return;
> +
> + vga_set_default_device(pdev);
> +}
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1711, hibmc_fixup_vgaarb);
> --
> 2.11.0
>
