[PATCH]] drm/amdgpu/gfx9: add gfxoff quirk

[Daniel Gomez <daniel@qtec.com>]

Disabling GFXOFF via the quirk list fixes a hardware lockup in
Ryzen V1605B, RAVEN 0x1002:0x15DD rev 0x83.

Signed-off-by: Daniel Gomez <daniel@qtec.com>
---

This patch is a continuation of the work here:
https://lkml.org/lkml/2021/2/3/122 where a hardware lockup was discussed and
a dma_fence deadlock was provoke as a side effect. To reproduce the issue
please refer to the above link.

The hardware lockup was introduced in 5.6-rc1 for our particular revision as it
wasn't part of the new blacklist. Before that, in kernel v5.5, this hardware was
working fine without any hardware lock because the GFXOFF was actually disabled
by the if condition for the CHIP_RAVEN case. So this patch, adds the 'Radeon
Vega Mobile Series [1002:15dd] (rev 83)' to the blacklist to disable the GFXOFF.

But besides the fix, I'd like to ask from where this revision comes from. Is it
an ASIC revision or is it hardcoded in the VBIOS from our vendor? From what I
can see, it comes from the ASIC and I wonder if somehow we can get an APU in the
future, 'not blacklisted', with the same problem. Then, should this table only
filter for the vendor and device and not the revision? Do you know if there are
any revisions for the 1002:15dd validated, tested and functional?

Logs:
[   27.708348] [drm] initializing kernel modesetting (RAVEN
0x1002:0x15DD 0x1002:0x15DD 0x83).
[   27.789156] amdgpu: ATOM BIOS: 113-RAVEN-115

Thanks in advance,
Daniel

 drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 65db88bb6cbc..319d4b99aec8 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -1243,6 +1243,8 @@ static const struct amdgpu_gfxoff_quirk amdgpu_gfxoff_quirk_list[] = {
 	{ 0x1002, 0x15dd, 0x103c, 0x83e7, 0xd3 },
 	/* GFXOFF is unstable on C6 parts with a VBIOS 113-RAVEN-114 */
 	{ 0x1002, 0x15dd, 0x1002, 0x15dd, 0xc6 },
+	/* GFXOFF provokes a hw lockup on 83 parts with a VBIOS 113-RAVEN-115 */
+	{ 0x1002, 0x15dd, 0x1002, 0x15dd, 0x83 },
 	{ 0, 0, 0, 0, 0 },
 };

--
2.30.1