On 05/12/17 18:32, Ben Skeggs wrote:
On Wed, Dec 6, 2017 at 12:30 AM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
On 04/12/17 18:37, Guillaume Tucker wrote:
If the firmware fails to load then ->fini() will be called before the
device has been initialised, causing the kernel to hang while trying
to write to a register. Add a test in ->fini() to avoid this issue.
This fixes a kernel hang on tegra124.
Fixes: b17de35a2ebbe ("drm/nouveau/bar: implement bar1 teardown")
Signed-off-by: Guillaume Tucker <guillaume.tucker@xxxxxxxxxxxxx>
CC: Ben Skeggs <bskeggs@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
index a3ba7f50198b..95e2aba64aad 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
@@ -43,9 +43,12 @@ gf100_bar_bar1_wait(struct nvkm_bar *base)
}
void
-gf100_bar_bar1_fini(struct nvkm_bar *bar)
+gf100_bar_bar1_fini(struct nvkm_bar *base)
{
- nvkm_mask(bar->subdev.device, 0x001704, 0x80000000, 0x00000000);
+ struct nvkm_device *device = base->subdev.device;
+
+ if (base->subdev.oneinit)
+ nvkm_mask(device, 0x001704, 0x80000000, 0x00000000);
}
void
I have tested this and it works for me. Thanks for fixing this! Would be
good to get Ben's ACK, but you can have my ...
I'd love to get a good explanation as to why it hangs without this change,
as, on the surface, it's not immediately obvious as to why it's hanging.
To be fair I'm not entirely sure either why this causes a hang, I
haven't read the TRM... The iomem has been mapped at this point,
so accessing the register should work. One clue is when you look
at _bar1_init(), the 0x1704 register is initialised with
some (device instance?) memory address. So it's possible that
the hardware does something special when you set this to 0 as in
_bar1_fini(), which may fail in particular if it was previously
not initialised with a valid address.
This is merely guesswork, would be interested to find out the
real explanation though.
Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Thanks!
Guillaume
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