> -----Original Message----- > From: Ben Crocker [mailto:bcrocker@xxxxxxxxxx] > Sent: Tuesday, April 24, 2018 3:30 PM > To: gregkh@xxxxxxxxxxxxxxxxxxx > Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; > stable@xxxxxxxxxxxxxxx > Subject: Re: FAILED: patch "[PATCH] drm/radeon: insist on 32-bit DMA for > Cedar on PPC64/PPC64LE" failed to apply to 4.16-stable tree > > (Third try, after turning on Plain Text mode in Gmail; apologies if you got this > more than once) > > Hi Greg, > > Thanks for the note. I think this is a case of the same change having been > checked in on different branches. I downloaded the linux-4.16.3 tarball, > unpacked it, and examined radeon_device.c; the correct change is there in > radeon_device_init (the four lines beginning "#ifdef CONFIG_PPC64"). > > Looking at the whole git log, I see two instances of exactly the same > patch: > > commit bcb0b981c5571744ac446a6c906aa05a28d21446 > Author: Ben Crocker <bcrocker@xxxxxxxxxx> > Date: Thu Feb 22 17:52:19 2018 -0500 > > drm/radeon: insist on 32-bit DMA for Cedar on PPC64/PPC64LE > > and > > commit 2c83029cda55a5e7665c7c6326909427d6a01350 > Author: Ben Crocker <bcrocker@xxxxxxxxxx> > Date: Thu Feb 22 17:52:19 2018 -0500 > > drm/radeon: insist on 32-bit DMA for Cedar on PPC64/PPC64LE > > A colleague of mine here at Red Hat thinks that no further action is > necessary; please let me know what you think. No further action is required. The patch was committed to drm-next for the next kernel and also ended up in drm-fixes for the current one at the time. Alex > > Thanks, > Ben > > > On Sun, Apr 22, 2018 at 4:19 AM, <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > The patch below does not apply to the 4.16-stable tree. > > If someone wants it applied there, or to any other stable or longterm > > tree, then please email the backport, including the original git > > commit id to <stable@xxxxxxxxxxxxxxx>. > > > > thanks, > > > > greg k-h > > > > ------------------ original commit in Linus's tree ------------------ > > > > From bcb0b981c5571744ac446a6c906aa05a28d21446 Mon Sep 17 00:00:00 > 2001 > > From: Ben Crocker <bcrocker@xxxxxxxxxx> > > Date: Thu, 22 Feb 2018 17:52:19 -0500 > > Subject: [PATCH] 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 > > > > 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@xxxxxxxxxx> > > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > > > diff --git a/drivers/gpu/drm/radeon/radeon_device.c > > b/drivers/gpu/drm/radeon/radeon_device.c > > index 7f40c6f7c4dd..e415d2c097a7 100644 > > --- a/drivers/gpu/drm/radeon/radeon_device.c > > +++ b/drivers/gpu/drm/radeon/radeon_device.c > > @@ -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)); > >