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

[Michel Dänzer]

On 2018-02-22 10:57 PM, Ben Crocker 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)) &&

Cedar is (like all Radeons from the last decade) always PCIe, so this
flags check is redundant FWIW.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer