Am Freitag, den 04.10.2019, 10:27 +0100 schrieb Russell King - ARM Linux admin: > On Thu, Oct 03, 2019 at 02:30:10PM +0300, Mike Rapoport wrote: > > On Thu, Oct 03, 2019 at 09:49:14AM +0100, Russell King - ARM Linux > > admin wrote: > > > On Thu, Oct 03, 2019 at 08:34:52AM +0300, Mike Rapoport wrote: > > > > (trimmed the CC) > > > > > > > > On Wed, Oct 02, 2019 at 06:14:11AM -0500, Adam Ford wrote: > > > > > On Wed, Oct 2, 2019 at 2:36 AM Mike Rapoport < > > > > > rppt@xxxxxxxxxxxxx> wrote: > > > > > > > > > > Before the patch: > > > > > > > > > > # cat /sys/kernel/debug/memblock/memory > > > > > 0: 0x10000000..0x8fffffff > > > > > # cat /sys/kernel/debug/memblock/reserved > > > > > 0: 0x10004000..0x10007fff > > > > > 34: 0x2fffff88..0x3fffffff > > > > > > > > > > > > > > > After the patch: > > > > > # cat /sys/kernel/debug/memblock/memory > > > > > 0: 0x10000000..0x8fffffff > > > > > # cat /sys/kernel/debug/memblock/reserved > > > > > 0: 0x10004000..0x10007fff > > > > > 36: 0x80000000..0x8fffffff > > > > > > > > I'm still not convinced that the memblock refactoring didn't > > > > uncovered an > > > > issue in etnaviv driver. > > > > > > > > Why moving the CMA area from 0x80000000 to 0x30000000 makes it > > > > fail? > > > > > > I think you have that the wrong way round. > > > > I'm relying on Adam's reports of working and non-working versions. > > According to that etnaviv works when CMA area is at 0x80000000 and > > does not > > work when it is at 0x30000000. > > > > He also sent logs a few days ago [1], they also confirm that. > > > > [1] > > https://lore.kernel.org/linux-mm/CAHCN7xJEvS2Si=M+BYtz+kY0M4NxmqDjiX9Nwq6_3GGBh3yg=w@xxxxxxxxxxxxxx/ > > Sorry, yes, you're right. Still, I've reported this same regression > a while back, and it's never gone away. > > > > > BTW, the code that complained about "command buffer outside > > > > valid memory > > > > window" has been removed by the commit 17e4660ae3d7 > > > > ("drm/etnaviv: > > > > implement per-process address spaces on MMUv2"). > > > > > > > > Could be that recent changes to MMU management of etnaviv > > > > resolve the > > > > issue? > > > > > > The iMX6 does not have MMUv2 hardware, it has MMUv1. With MMUv1 > > > hardware requires command buffers within the first 2GiB of > > > physical > > > RAM. > > > > I've mentioned that patch because it removed the check for cmdbuf > > address > > for MMUv1: > > > > @@ -785,15 +768,7 @@ int etnaviv_gpu_init(struct etnaviv_gpu *gpu) > > PAGE_SIZE); > > if (ret) { > > dev_err(gpu->dev, "could not create command > > buffer\n"); > > - goto unmap_suballoc; > > - } > > - > > - if (!(gpu->identity.minor_features1 & > > chipMinorFeatures1_MMU_VERSION) && > > - etnaviv_cmdbuf_get_va(&gpu->buffer, &gpu- > > >cmdbuf_mapping) > 0x80000000) { > > - ret = -EINVAL; > > - dev_err(gpu->dev, > > - "command buffer outside valid memory > > window\n"); > > - goto free_buffer; > > + goto fail; > > } > > > > /* Setup event management */ > > > > > > I really don't know how etnaviv works, so I hoped that people who > > understand it would help. > > From what I can see, removing that check is a completely insane thing > to do, and I note that these changes are _not_ described in the > commit > message. The problem was known about _before_ (June 22) the patch > was > created (July 5). > > Lucas, please can you explain why removing the above check, which is > well known to correctly trigger on various platforms to prevent > incorrect GPU behaviour, is safe? It isn't. It's a pretty big oversight in this commit to remove this check. It can't be done at the same spot in the code anymore, as we don't have a mapping context at this time anymore, but it should have moved into etnaviv_iommu_context_init(). I'll send a patch to fix this up. Regards, Lucas
