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

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

8e3f1b1d82 (Russell Currey)

and

253fd51e2f (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@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Ben Crocker 2018-02-22 17:52:19 -05:00 committed by Alex Deucher
parent 421334a847
commit bcb0b981c5
1 changed files with 4 additions and 0 deletions
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4
drivers/gpu/drm/radeon/radeon_device.c
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@ -1366,6 +1366,10 @@ 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->family == CHIP_CEDAR)
rdev->need_dma32 = true;
#endif
dma_bits = rdev->need_dma32 ? 32 : 40;
r = pci_set_dma_mask(rdev->pdev, DMA_BIT_MASK(dma_bits));