[PATCH] drm/amdgpu: Workaround RCC_DEV0_EPF0_STRAP0 access issue for SRIOV

[Khaire, Rohit]

[AMD Public Use]

Hi Alex,

I discussed this with my team, we are fine with PCI_REVISION_ID for SRIOV.

I am resending my patch with the change you suggested.

Thanks
Rohit

-----Original Message-----
From: Alex Deucher <alexdeucher at gmail.com> 
Sent: September 14, 2020 1:16 AM
To: Khaire, Rohit <Rohit.Khaire at amd.com>
Cc: amd-gfx list <amd-gfx at lists.freedesktop.org>
Subject: Re: [PATCH] drm/amdgpu: Workaround RCC_DEV0_EPF0_STRAP0 access issue for SRIOV

On Fri, Sep 11, 2020 at 6:03 PM Rohit Khaire <rohit.khaire at amd.com> wrote:
>
> Signed-off-by: Rohit Khaire <rohit.khaire at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c 
> b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
> index 7429f30398b9..fdfa075e6d5a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
> +++ b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
> @@ -51,8 +51,20 @@ static void nbio_v2_3_remap_hdp_registers(struct 
> amdgpu_device *adev)
>
>  static u32 nbio_v2_3_get_rev_id(struct amdgpu_device *adev)  {
> -       u32 tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
> +       u32 tmp;
>
> +       /*
> +        * On SRIOV VF RCC_DEV0_EPF0_STRAP is blocked.
> +        * So we read rev_id from PCI config space.
> +        */
> +       if (amdgpu_sriov_vf(adev)) {
> +               pci_read_config_dword(adev->pdev, PCI_REVISION_ID, &tmp);

This is not going to do what you want.  The pci revision id is not the
same as the ati rev id.  If you actually want the pci revision id, we
already have it in adev->pdev->revision, no need to fetch it directly.

Alex


> +               /* Revision ID is the least significant 8 bits */
> +               tmp &= 0xFF;
> +               return tmp;
> +       }
> +
> +       tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
>         tmp &= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0_MASK;
>         tmp >>= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0__SHIFT;
>
> --
> 2.17.1
>
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