rust: pci: display symbolic PCI vendor names

The Display implementation for Vendor was forwarding directly to Debug
printing, resulting in raw hex values instead of PCI Vendor strings.

Improve things by doing a stringify!() call for each PCI Vendor item.
This now prints symbolic names such as "NVIDIA", instead of
"Vendor(0x10de)". It still falls back to Debug formatting for unknown
class values.

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
[ Remove #[inline] for Vendor::fmt(). - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/kernel/pci/id.rs

@@ -135,6 +135,17 @@ macro_rules! define_all_pci_vendors {
                 pub const $variant: Self = Self($binding as u16);
             )+
         }
+
+        impl fmt::Display for Vendor {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                match self {
+                    $(
+                        &Self::$variant => write!(f, stringify!($variant)),
+                    )+
+                    _ => <Self as fmt::Debug>::fmt(self, f),
+                }
+            }
+        }
     };
 }
 
@@ -160,13 +171,6 @@ impl fmt::Debug for Vendor {
     }
 }
 
-impl fmt::Display for Vendor {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        <Self as fmt::Debug>::fmt(self, f)
-    }
-}
-
 define_all_pci_classes! {
     NOT_DEFINED                = bindings::PCI_CLASS_NOT_DEFINED,                // 0x000000
     NOT_DEFINED_VGA            = bindings::PCI_CLASS_NOT_DEFINED_VGA,            // 0x000100