[PATCH] Revert "Revert "drm/amdgpu: use the BAR if possible in amdgpu_device_vram_access v2""

[Alex Deucher]

On Tue, May 5, 2020 at 2:57 PM Kent Russell <kent.russell at amd.com> wrote:
>
> This reverts commit e71391880aa72709fac53f98d96a2d4e8875b9fa.
>
> The RAS issue at the base of this problem appears to have been addressed
>
> Signed-off-by: Kent Russell <kent.russell at amd.com>
> Change-Id: I338a985e19cae8e103bd44b0f238314e9460d396

Would probably be cleaner to just re-apply the original patch with an
additional note in the commit than to revert the revert.  Either way:
Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 26 ++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index caa38e7d502e..bf302c799832 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -255,6 +255,32 @@ void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
>         uint32_t hi = ~0;
>         uint64_t last;
>
> +
> +#ifdef CONFIG_64BIT
> +       last = min(pos + size, adev->gmc.visible_vram_size);
> +       if (last > pos) {
> +               void __iomem *addr = adev->mman.aper_base_kaddr + pos;
> +               size_t count = last - pos;
> +
> +               if (write) {
> +                       memcpy_toio(addr, buf, count);
> +                       mb();
> +                       amdgpu_asic_flush_hdp(adev, NULL);
> +               } else {
> +                       amdgpu_asic_invalidate_hdp(adev, NULL);
> +                       mb();
> +                       memcpy_fromio(buf, addr, count);
> +               }
> +
> +               if (count == size)
> +                       return;
> +
> +               pos += count;
> +               buf += count / 4;
> +               size -= count;
> +       }
> +#endif
> +
>         spin_lock_irqsave(&adev->mmio_idx_lock, flags);
>         for (last = pos + size; pos < last; pos += 4) {
>                 uint32_t tmp = pos >> 31;
> --
> 2.17.1
>
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