[PATCH] drm/radeon: Don't flush the GART TLB if rdev->gart.ptr == NULL

[Alex Deucher]

On Thu, Jul 2, 2015 at 9:02 PM, Michel Dänzer <michel at daenzer.net> wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> This can be the case when the GPU is powered off, e.g. via vgaswitcheroo
> or runpm. When the GPU is powered up again, radeon_gart_table_vram_pin
> flushes the TLB after setting rdev->gart.ptr to non-NULL.
>
> Fixes panic on powering off R7xx GPUs.

This is a nice safely measure, but the underlying issue is that the
acpiphp code is broken again on some boards and attempts to remove the
device after the driver has already suspended the driver for runtime
pm.  So the the driver's pci_remove callback ends up being called
after the driver has already been suspended and the the hw has been
disabled.

Alex

>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61529
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>  drivers/gpu/drm/radeon/radeon_gart.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c
> index 5450fa9..c4777c8 100644
> --- a/drivers/gpu/drm/radeon/radeon_gart.c
> +++ b/drivers/gpu/drm/radeon/radeon_gart.c
> @@ -260,8 +260,10 @@ void radeon_gart_unbind(struct radeon_device *rdev, unsigned offset,
>                         }
>                 }
>         }
> -       mb();
> -       radeon_gart_tlb_flush(rdev);
> +       if (rdev->gart.ptr) {
> +               mb();
> +               radeon_gart_tlb_flush(rdev);
> +       }
>  }
>
>  /**
> @@ -306,8 +308,10 @@ int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
>                         page_base += RADEON_GPU_PAGE_SIZE;
>                 }
>         }
> -       mb();
> -       radeon_gart_tlb_flush(rdev);
> +       if (rdev->gart.ptr) {
> +               mb();
> +               radeon_gart_tlb_flush(rdev);
> +       }
>         return 0;
>  }
>
> --
> 2.1.4
>
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