linux-kernel - [PATCH] drm/nouveau/mmu/nv4a: use nv04 mmu rather than the nv44 one

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Message-Id: <20170318202310.4940-1-imirkin@alum.mit.edu>
Date:   Sat, 18 Mar 2017 16:23:10 -0400
From:   Ilia Mirkin <imirkin@...m.mit.edu>
To:     Ben Skeggs <bskeggs@...hat.com>, Dave Airlie <airlied@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Ilia Mirkin <imirkin@...m.mit.edu>
Subject: [PATCH] drm/nouveau/mmu/nv4a: use nv04 mmu rather than the nv44 one

The NV4A (aka NV44A) is an oddity in the family. It only comes in AGP
and PCI varieties, rather than a core PCIE chip with a bridge for
AGP/PCI as necessary. As a result, it appears that the MMU is also
non-functional. For AGP cards, the vast majority of the NV4A lineup,
this worked out since we force AGP cards to use the nv04 mmu. However
for PCI variants, this did not work.

Switching to the NV04 MMU makes it work like a charm. Thanks to mwk for
the suggestion. This should be a no-op for NV4A AGP boards, as they were
using it already.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70388
Signed-off-by: Ilia Mirkin <imirkin@...m.mit.edu>
Cc: stable@...r.kernel.org
---

OK, so I'm not 100% sure about my claims, but I don't have the necessary
hardware to test it out. Right now, AGP nv41+ boards are getting the nv04
mmu, while PCI nv41+ boards are getting the PCIE one. Perhaps this works
for them, however such boards are rare, and I don't have one. Perhaps all
PCI boards should be routed to the nv04 mmu, not just the NV4A ones.

 drivers/gpu/drm/nouveau/nvkm/engine/device/base.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/base.c b/drivers/gpu/drm/nouveau/nvkm/engine/device/base.c
index 273562d..0fc41db 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/device/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/base.c
@@ -714,7 +714,7 @@ nv4a_chipset = {
 	.i2c = nv04_i2c_new,
 	.imem = nv40_instmem_new,
 	.mc = nv44_mc_new,
-	.mmu = nv44_mmu_new,
+	.mmu = nv04_mmu_new,
 	.pci = nv40_pci_new,
 	.therm = nv40_therm_new,
 	.timer = nv41_timer_new,
-- 
2.10.2