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From: Timur Tabi <ttabi@nvidia.com>
To: Lyude Paul <lyude@redhat.com>, Dave Airlie <airlied@redhat.com>,
	<nouveau@lists.freedesktop.org>
Subject: [PATCH 2/6] drm/nouveau/bios: specify correct display fuse register
 for Ampere and Ada
Date: Tue, 7 Apr 2026 14:21:18 -0500
Message-ID: <20260407192122.3055293-3-ttabi@nvidia.com>
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The NV_FUSE_STATUS_OPT_DISPLAY register is used to determine whether
the GPU has display hardware.  The current code that normally reads
this register is instead hard-coded to check for GA100 vs later GPUs.
Since this function is called only on pre-Hopper GPUs, and this
if-statement applies only to GA100 and later, the check works
because GA100 is the only non-display Ampere and Ada GPU.

However, there actually is a register that can be read, so we should
use it.

Fixes: a34632482f1e ("drm/nouveau/bios/ga10[024]: initial support")
Signed-off-by: Timur Tabi <ttabi@nvidia.com>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowramin.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowramin.c b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowramin.c
index d5411d176e3a..0d9e6cdd6119 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowramin.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowramin.c
@@ -65,13 +65,14 @@ pramin_init(struct nvkm_bios *bios, const char *name)
 
 	/* we can't get the bios image pointer without PDISP */
 	if (device->card_type >= GA100)
-		addr = device->chipset == 0x170; /*XXX: find the fuse reg for this */
+		addr = nvkm_rd32(device, 0x820c04);
 	else
 	if (device->card_type >= GM100)
 		addr = nvkm_rd32(device, 0x021c04);
 	else
 	if (device->card_type >= NV_C0)
 		addr = nvkm_rd32(device, 0x022500);
+
 	if (addr & 0x00000001) {
 		nvkm_debug(subdev, "... display disabled\n");
 		return ERR_PTR(-ENODEV);
-- 
2.53.0