Commit 2c83029c authored Feb 22, 2018 by Ben Crocker Committed by Alex Deucher Feb 22, 2018

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

8e3f1b1d (Russell Currey)

and

253fd51e (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

parent 4909c6de

drivers/gpu/drm/radeon/radeon_device.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1365,6 +1365,10 @@ 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));