[PATCH v4 2/3] gpu: nova-core: avoid probing non-display/compute PCI functions

[John Hubbard <jhubbard@nvidia.com>]

NovaCore has so far been too imprecise about figuring out if .probe()
has found a supported PCI PF (Physical Function). By that I mean:
.probe() sets up BAR0 (which involves a lot of very careful devres and
Device<Bound> details behind the scenes). And then if it is dealing with
a non-supported device such as the .1 audio PF on many GPUs, it fails
out due to an unexpected BAR0 size. We have been fortunate that the BAR0
sizes are different.

Really, we should be filtering on PCI class ID instead. These days I
think we can confidently pick out Nova's supported PF's via PCI class
ID. And if not, then we'll revisit.

The approach here is to filter on "Display VGA" or "Display 3D", which
is how PCI class IDs express "this is a modern GPU's PF".

Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/driver.rs | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 274989ea1fb4..b60c9defa9d1 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -1,6 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use kernel::{auxiliary, bindings, c_str, device::Core, pci, prelude::*, sizes::SZ_16M, sync::Arc};
+use kernel::{
+    auxiliary, bindings, c_str, device::Core, pci, pci::Class, pci::ClassMask, prelude::*,
+    sizes::SZ_16M, sync::Arc,
+};
 
 use crate::gpu::Gpu;
 
@@ -18,10 +21,25 @@ pub(crate) struct NovaCore {
     PCI_TABLE,
     MODULE_PCI_TABLE,
     <NovaCore as pci::Driver>::IdInfo,
-    [(
-        pci::DeviceId::from_id(bindings::PCI_VENDOR_ID_NVIDIA, bindings::PCI_ANY_ID as u32),
-        ()
-    )]
+    [
+        // Modern NVIDIA GPUs will show up as either VGA or 3D controllers.
+        (
+            pci::DeviceId::from_class_and_vendor(
+                Class::DISPLAY_VGA,
+                ClassMask::ClassSubclass,
+                bindings::PCI_VENDOR_ID_NVIDIA
+            ),
+            ()
+        ),
+        (
+            pci::DeviceId::from_class_and_vendor(
+                Class::DISPLAY_3D,
+                ClassMask::ClassSubclass,
+                bindings::PCI_VENDOR_ID_NVIDIA
+            ),
+            ()
+        ),
+    ]
 );
 
 impl pci::Driver for NovaCore {
-- 
2.50.1