ACK: [SRU][Zesty][PATCH] UBUNTU: SAUCE: PCI: Support hibmc VGA cards behind a misbehaving HiSilicon bridge

[Stefan Bader]

On 29.06.2017 05:45, Daniel Axtens wrote:
> BugLink: https://bugs.launchpad.net/bugs/1698706
> 
> The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) that
> are not spec-compliant: the VGA Enable bit is set to 0 in hardware
> and writes do not change it.
> 
> This stops VGA arbitrartion from marking a VGA card behind the bridge
> as a boot device, and therefore breaks Xorg auto-configuration.
> 
> 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 at hisilicon.com>
> Cc: Rongrong Zou <zourongrong at gmail.com>
> Signed-off-by: Daniel Axtens <daniel.axtens at canonical.com>

Acked-by: Stefan Bader <stefan.bader at canonical.com>

> ---

Sounds like sufficient effort has been made to restrict impact to a specific set
of hardware. So should be easy to verify.

>  drivers/pci/quirks.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 2a03cd03d9c2..e40684ae7335 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"
>  
> @@ -4669,3 +4670,48 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2030, quirk_no_aersid);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2031, quirk_no_aersid);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2032, quirk_no_aersid);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2033, quirk_no_aersid);
> +
> +/*
> + * The hibmc card on a HiSilicon D05 board sits behind a non-compliant
> + * bridge. The bridge has the PCI_BRIDGE_CTL_VGA config bit fixed at 0
> + * in hardware. 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);
> 


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