This is a note to let you know that I've just added the patch titled

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

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: drm-radeon-insist-on-32-bit-dma-for-cedar-on-ppc64-ppc64le.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 2c83029cda55a5e7665c7c6326909427d6a01350 Mon Sep 17 00:00:00 2001

From: Ben Crocker bcrocker@redhat.com Date: Thu, 22 Feb 2018 17:52:19 -0500 Subject: drm/radeon: insist on 32-bit DMA for Cedar on PPC64/PPC64LE

From: Ben Crocker bcrocker@redhat.com

commit 2c83029cda55a5e7665c7c6326909427d6a01350 upstream.

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@redhat.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/gpu/drm/radeon/radeon_device.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/radeon/radeon_device.c +++ b/drivers/gpu/drm/radeon/radeon_device.c @@ -1397,6 +1397,10 @@ int radeon_device_init(struct radeon_dev 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));

Patches currently in stable-queue which might be from bcrocker@redhat.com are

queue-4.14/drm-radeon-insist-on-32-bit-dma-for-cedar-on-ppc64-ppc64le.patch