gpu: nova-core: preserve error information in gpu_name()

Change gpu_name() to return a Result instead of an Option. This avoids
silently discarding error information when parsing the GPU name string
from the GSP.

Update the callsite to log a warning with the error details on failure,
rather than just displaying "invalid GPU name".

Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Link: https://patch.msgid.link/20260108005811.86014-2-jhubbard@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

drivers/gpu/nova-core/gsp/boot.rs

@@ -238,11 +238,10 @@ impl super::Gsp {
 
         // Obtain and display basic GPU information.
         let info = commands::get_gsp_info(&mut self.cmdq, bar)?;
-        dev_info!(
-            pdev.as_ref(),
-            "GPU name: {}\n",
-            info.gpu_name().unwrap_or("invalid GPU name")
-        );
+        match info.gpu_name() {
+            Ok(name) => dev_info!(pdev.as_ref(), "GPU name: {}\n", name),
+            Err(e) => dev_warn!(pdev.as_ref(), "GPU name unavailable: {:?}\n", e),
+        }
 
         Ok(())
     }

drivers/gpu/nova-core/gsp/commands.rs

@@ -2,7 +2,9 @@
 
 use core::{
     array,
-    convert::Infallible, //
+    convert::Infallible,
+    ffi::FromBytesUntilNulError,
+    str::Utf8Error, //
 };
 
 use kernel::{
@@ -204,13 +206,27 @@ impl MessageFromGsp for GetGspStaticInfoReply {
     }
 }
 
+/// Error type for [`GetGspStaticInfoReply::gpu_name`].
+#[derive(Debug)]
+pub(crate) enum GpuNameError {
+    /// The GPU name string does not contain a null terminator.
+    NoNullTerminator(FromBytesUntilNulError),
+
+    /// The GPU name string contains invalid UTF-8.
+    #[expect(dead_code)]
+    InvalidUtf8(Utf8Error),
+}
+
 impl GetGspStaticInfoReply {
-    /// Returns the name of the GPU as a string, or `None` if the string given by the GSP was
-    /// invalid.
-    pub(crate) fn gpu_name(&self) -> Option<&str> {
+    /// Returns the name of the GPU as a string.
+    ///
+    /// Returns an error if the string given by the GSP does not contain a null terminator or
+    /// contains invalid UTF-8.
+    pub(crate) fn gpu_name(&self) -> core::result::Result<&str, GpuNameError> {
         CStr::from_bytes_until_nul(&self.gpu_name)
-            .ok()
-            .and_then(|cstr| cstr.to_str().ok())
+            .map_err(GpuNameError::NoNullTerminator)?
+            .to_str()
+            .map_err(GpuNameError::InvalidUtf8)
     }
 }