[PATCH 0/2] Adjust AMD GPU ATS quirks

[Deucher, Alexander]

[AMD Public Use]

> -----Original Message-----
> From: Bjorn Helgaas <helgaas at kernel.org>
> Sent: Tuesday, January 14, 2020 6:42 PM
> To: Alex Deucher <alexdeucher at gmail.com>
> Cc: amd-gfx at lists.freedesktop.org; linux-pci at vger.kernel.org; Deucher,
> Alexander <Alexander.Deucher at amd.com>
> Subject: Re: [PATCH 0/2] Adjust AMD GPU ATS quirks
> 
> On Tue, Jan 14, 2020 at 03:55:21PM -0500, Alex Deucher wrote:
> > We've root caused the issue and clarified the quirk.
> > This also adds a new quirk for a new GPU.
> >
> > Alex Deucher (2):
> >   pci: Clarify ATS quirk
> >   pci: add ATS quirk for navi14 board (v2)
> >
> >  drivers/pci/quirks.c | 32 +++++++++++++++++++++++++-------
> >  1 file changed, 25 insertions(+), 7 deletions(-)
> 
> I propose the following, which I intend to be functionally identical.
> It just doesn't repeat the pci_info() and pdev->ats_cap = 0.
> 

Works for me.  Thanks!

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> commit 998c4f7975b0 ("PCI: Mark AMD Navi14 GPU rev 0xc5 ATS as broken")
> Author: Bjorn Helgaas <bhelgaas at google.com>
> Date:   Tue Jan 14 17:09:28 2020 -0600
> 
>     PCI: Mark AMD Navi14 GPU rev 0xc5 ATS as broken
> 
>     To account for parts of the chip that are "harvested" (disabled) due to
>     silicon flaws, caches on some AMD GPUs must be initialized before ATS is
>     enabled.
> 
>     ATS is normally enabled by the IOMMU driver before the GPU driver loads,
> so
>     this cache initialization would have to be done in a quirk, but that's too
>     complex to be practical.
> 
>     For Navi14 (device ID 0x7340), this initialization is done by the VBIOS,
>     but apparently some boards went to production with an older VBIOS that
>     doesn't do it.  Disable ATS for those boards.
> 
> 
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.
> kernel.org%2Fr%2F20200114205523.1054271-3-
> alexander.deucher%40amd.com&data=02%7C01%7Calexander.deucher
> %40amd.com%7C7bbf2f086ba64a68891e08d7994b5216%7C3dd8961fe4884e6
> 08e11a82d994e183d%7C0%7C0%7C637146421098328112&sdata=aLaNuiJ
> pB4dYatxvBJuC%2Blk90Dhl4qd5jvLp75ZUDns%3D&reserved=0
>     Bug:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2Fissues%2F1015&data=02%7C01%
> 7Calexander.deucher%40amd.com%7C7bbf2f086ba64a68891e08d7994b5216
> %7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C63714642109832811
> 2&sdata=QgCFuWKp8Dg3lpQhXCb2z4qmukdqkiX0e3%2BRz%2FcPkg0%3
> D&reserved=0
>     See-also: d28ca864c493 ("PCI: Mark AMD Stoney Radeon R7 GPU ATS as
> broken")
>     See-also: 9b44b0b09dec ("PCI: Mark AMD Stoney GPU ATS as broken")
>     Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index
> 4937a088d7d8..fbeb9f73ef28 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5074,18 +5074,25 @@
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, 0x0422,
> quirk_no_ext_tags);
> 
>  #ifdef CONFIG_PCI_ATS
>  /*
> - * Some devices have a broken ATS implementation causing IOMMU stalls.
> - * Don't use ATS for those devices.
> + * Some devices require additional driver setup to enable ATS.  Don't
> + use
> + * ATS for those devices as ATS will be enabled before the driver has
> + had a
> + * chance to load and configure the device.
>   */
> -static void quirk_no_ats(struct pci_dev *pdev)
> +static void quirk_amd_harvest_no_ats(struct pci_dev *pdev)
>  {
> -	pci_info(pdev, "disabling ATS (broken on this device)\n");
> +	if (pdev->device == 0x7340 && pdev->revision != 0xc5)
> +		return;
> +
> +	pci_info(pdev, "disabling ATS\n");
>  	pdev->ats_cap = 0;
>  }
> 
>  /* AMD Stoney platform GPU */
> -DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x98e4, quirk_no_ats); -
> DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x6900, quirk_no_ats);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x98e4,
> +quirk_amd_harvest_no_ats);
> +/* AMD Iceland dGPU */
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x6900,
> +quirk_amd_harvest_no_ats);
> +/* AMD Navi14 dGPU */
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7340,
> +quirk_amd_harvest_no_ats);
>  #endif /* CONFIG_PCI_ATS */
> 
>  /* Freescale PCIe doesn't support MSI in RC mode */