On Tue, Sep 17, 2019 at 04:07:54PM +1000, Ben Skeggs wrote: > On Tue, 17 Sep 2019 at 00:36, Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > > > > From: Thierry Reding <treding@xxxxxxxxxx> > > > > Hi Ben, > > > > I messed up the ordering of patches in my tree a bit, so these two fixes > > got separated from the others. I don't consider these particularily > > urgent because the crash that the first one fixes only happens on gp10b > > which we don't enable by default yet and the second patch fixes a crash > > that only happens on module unload (or driver unbind, more accurately), > > which isn't a terribly common thing to do. > > > > I'll be sending out fixes shortly to make the GP10B work more properly > > on a wider range of Jetson TX2 devices and enable it by default. > > > > One thing to mention is that I'm not exactly sure if the first patch is > > the right thing to do. I haven't seen any issues after that change, but > > I'm also not exactly sure I understand what BAR2 is used for, so I don't > > know if I would've even covered those code paths (other than the one > > causing the crash at probe time) in my tests. > BAR2 on dGPUs is used to map kernel-level GPU objects in VRAM so they > can be accessed by the driver. It's pretty much a smaller version of > BAR1, but intended for a different purpose. > > On dGPUs, there's a couple of places (fault buffer address, and fault > method buffer on volta) where the GPU wants PRI regs to be poked with > an offset within BAR2 rather than an aperture+offset combination. I'm > not 100% sure what Tegra parts do here, but presumably if it's working > for you, they're happy to just accept a system memory address instead. > > I guess this would be the right thing to do here in that situation. > The more obvious (from a "reading the code" POV) thing to do would be > to write Tegra-specific versions of the functions that use > nvkm_memory_bar2() to perform this mapping, and use nvkm_memory_addr() > instead but I'm not sure if we need/want to go to that effort. It's > conceivable it could be required at some point. Yeah, that sounds slightly more correct. I'll look into it and see if I can come up with something. Thierry > > Ben. > > > > > It'd be great to get Lyude's feedback on the second patch, since that > > call to pci_disable_device() was rather oddly placed and I'm not sure if > > that was essential for things to work or whether the slightly different > > point in time where it's called after this patch is also okay. It looks > > to me like it should work fine, but I don't currently have a way to test > > this on desktop GPUs. > > > > Thierry > > > > Thierry Reding (2): > > drm/nouveau: tegra: Fix NULL pointer dereference > > drm/nouveau: tegra: Do not try to disable PCI device > > > > drivers/gpu/drm/nouveau/nouveau_drm.c | 3 +- > > .../drm/nouveau/nvkm/subdev/instmem/gk20a.c | 30 +++++++++++++++++++ > > 2 files changed, 31 insertions(+), 2 deletions(-) > > > > -- > > 2.23.0 > > > > _______________________________________________ > > Nouveau mailing list > > Nouveau@xxxxxxxxxxxxxxxxxxxxx > > https://lists.freedesktop.org/mailman/listinfo/nouveau
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