[PATCH] drm/radeon: insist on 32-bit DMA for Cedar on PPC64/PPC64LE

[Alex Deucher]

On Thu, Feb 22, 2018 at 4:51 PM, Ben Crocker <bcrocker at redhat.com> wrote:
> In radeon_device_init, set the need_dma32 flag for Cedar chips
> (e.g. FirePro 2270).  This fixes, or at least works around, a bug
> on PowerPC exposed by last year's commits
>
> 8e3f1b1d8255105f31556aacf8aeb6071b00d469 (Russell Currey)
>
> and
>
> 253fd51e2f533552ae35a0c661705da6c4842c1b (Alistair Popple)
>
> which enabled the 64-bit DMA iommu bypass.
>
> This caused the device to freeze, in some cases unrecoverably, and is
> the subject of several bug reports internal to Red Hat.
>
> Signed-off-by: Ben Crocker <bcrocker at redhat.com>
> ---
>  drivers/gpu/drm/radeon/radeon_device.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
> index ffc10cadcf34..ba7435bcd208 100644
> --- a/drivers/gpu/drm/radeon/radeon_device.c
> +++ b/drivers/gpu/drm/radeon/radeon_device.c
> @@ -1397,6 +1397,11 @@ int radeon_device_init(struct radeon_device *rdev,
>         if ((rdev->flags & RADEON_IS_PCI) &&
>             (rdev->family <= CHIP_RS740))
>                 rdev->need_dma32 = true;
> +#ifdef CONFIG_PPC64
> +       if ((rdev->flags & (RADEON_IS_PCI | RADEON_IS_PCIE)) &&
> +           (rdev->family == CHIP_CEDAR))
> +               rdev->need_dma32 = true;
> +#endif

You can drop the PCI and PCIE checks and just check the family.

Alex

>
>         dma_bits = rdev->need_dma32 ? 32 : 40;
>         r = pci_set_dma_mask(rdev->pdev, DMA_BIT_MASK(dma_bits));
> --
> 2.13.6
>
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