Re: [PATCH] drm/nouveau/subdev/bus: Ratelimit logging for fault errors

[Lyude Paul <lyude@redhat.com>]

Mhhh - looks like it goes far back enough I probably should just Cc it without
a version tag and see how far it applies for greg. Will do that


On Wed, 2022-05-04 at 14:49 -0400, Lyude Paul wrote:
> On Tue, 2022-05-03 at 21:23 +0200, Karol Herbst wrote:
> > not able to hit any error on my machine, but regardless:
> > 
> > Reviewed-by: Karol Herbst <kherbst@redhat.com>
> > 
> > I suspect there are more places where we could put it, but we can add
> > those later.
> > 
> > Anyway, I think it's valuable to push it through fixes, not sure how
> > far back we want to CC stable though.
> 
> JFYI - dim fixes can figure this out if you just give it the commit that
> introduced the issue.
> 
> Anyway, will push this upstream in a moment
> 
> > 
> > On Fri, Apr 29, 2022 at 9:54 PM Lyude Paul <lyude@redhat.com> wrote:
> > > 
> > > There's plenty of ways to fudge the GPU when developing on nouveau by
> > > mistake, some of which can result in nouveau seriously spamming dmesg
> > > with
> > > fault errors. This can be somewhat annoying, as it can quickly overrun
> > > the
> > > message buffer (or your terminal emulator's buffer) and get rid of
> > > actually
> > > useful feedback from the driver. While working on my new atomic only MST
> > > branch, I ran into this issue a couple of times.
> > > 
> > > So, let's fix this by adding nvkm_error_ratelimited(), and using it to
> > > ratelimit errors from faults. This should be fine for developers, since
> > > it's nearly always only the first few faults that we care about seeing.
> > > Plus, you can turn off rate limiting in the kernel if you really need
> > > to.
> > > 
> > > Signed-off-by: Lyude Paul <lyude@redhat.com>
> > > ---
> > >  drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h |  2 ++
> > >  drivers/gpu/drm/nouveau/nvkm/subdev/bus/gf100.c    | 14 +++++++-------
> > >  drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv31.c     |  6 +++---
> > >  drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv50.c     |  6 +++---
> > >  4 files changed, 15 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h
> > > b/drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h
> > > index 1665738948fb..96113c8bee8c 100644
> > > --- a/drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h
> > > +++ b/drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h
> > > @@ -62,4 +62,6 @@ void nvkm_subdev_intr(struct nvkm_subdev *);
> > >  #define nvkm_debug(s,f,a...) nvkm_printk((s), DEBUG,   info, f, ##a)
> > >  #define nvkm_trace(s,f,a...) nvkm_printk((s), TRACE,   info, f, ##a)
> > >  #define nvkm_spam(s,f,a...)  nvkm_printk((s),  SPAM,    dbg, f, ##a)
> > > +
> > > +#define nvkm_error_ratelimited(s,f,a...) nvkm_printk((s), ERROR,
> > > err_ratelimited, f, ##a)
> > >  #endif
> > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/gf100.c
> > > b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/gf100.c
> > > index 53a6651ac225..80b5aaceeaad 100644
> > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/gf100.c
> > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/gf100.c
> > > @@ -35,13 +35,13 @@ gf100_bus_intr(struct nvkm_bus *bus)
> > >                 u32 addr = nvkm_rd32(device, 0x009084);
> > >                 u32 data = nvkm_rd32(device, 0x009088);
> > > 
> > > -               nvkm_error(subdev,
> > > -                          "MMIO %s of %08x FAULT at %06x [ %s%s%s]\n",
> > > -                          (addr & 0x00000002) ? "write" : "read", data,
> > > -                          (addr & 0x00fffffc),
> > > -                          (stat & 0x00000002) ? "!ENGINE " : "",
> > > -                          (stat & 0x00000004) ? "PRIVRING " : "",
> > > -                          (stat & 0x00000008) ? "TIMEOUT " : "");
> > > +               nvkm_error_ratelimited(subdev,
> > > +                                      "MMIO %s of %08x FAULT at %06x [
> > > %s%s%s]\n",
> > > +                                      (addr & 0x00000002) ? "write" :
> > > "read", data,
> > > +                                      (addr & 0x00fffffc),
> > > +                                      (stat & 0x00000002) ? "!ENGINE "
> > > :
> > > "",
> > > +                                      (stat & 0x00000004) ? "PRIVRING "
> > > :
> > > "",
> > > +                                      (stat & 0x00000008) ? "TIMEOUT "
> > > :
> > > "");
> > > 
> > >                 nvkm_wr32(device, 0x009084, 0x00000000);
> > >                 nvkm_wr32(device, 0x001100, (stat & 0x0000000e));
> > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv31.c
> > > b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv31.c
> > > index ad8da523bb22..c75e463f3501 100644
> > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv31.c
> > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv31.c
> > > @@ -45,9 +45,9 @@ nv31_bus_intr(struct nvkm_bus *bus)
> > >                 u32 addr = nvkm_rd32(device, 0x009084);
> > >                 u32 data = nvkm_rd32(device, 0x009088);
> > > 
> > > -               nvkm_error(subdev, "MMIO %s of %08x FAULT at %06x\n",
> > > -                          (addr & 0x00000002) ? "write" : "read", data,
> > > -                          (addr & 0x00fffffc));
> > > +               nvkm_error_ratelimited(subdev, "MMIO %s of %08x FAULT at
> > > %06x\n",
> > > +                                      (addr & 0x00000002) ? "write" :
> > > "read", data,
> > > +                                      (addr & 0x00fffffc));
> > > 
> > >                 stat &= ~0x00000008;
> > >                 nvkm_wr32(device, 0x001100, 0x00000008);
> > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv50.c
> > > b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv50.c
> > > index 3a1e45adeedc..2055d0b100d3 100644
> > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv50.c
> > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bus/nv50.c
> > > @@ -60,9 +60,9 @@ nv50_bus_intr(struct nvkm_bus *bus)
> > >                 u32 addr = nvkm_rd32(device, 0x009084);
> > >                 u32 data = nvkm_rd32(device, 0x009088);
> > > 
> > > -               nvkm_error(subdev, "MMIO %s of %08x FAULT at %06x\n",
> > > -                          (addr & 0x00000002) ? "write" : "read", data,
> > > -                          (addr & 0x00fffffc));
> > > +               nvkm_error_ratelimited(subdev, "MMIO %s of %08x FAULT at
> > > %06x\n",
> > > +                                      (addr & 0x00000002) ? "write" :
> > > "read", data,
> > > +                                      (addr & 0x00fffffc));
> > > 
> > >                 stat &= ~0x00000008;
> > >                 nvkm_wr32(device, 0x001100, 0x00000008);
> > > --
> > > 2.35.1
> > > 
> > 
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat