[PATCH v2 15/32] gpu: nova-core: gsp: add status-only GMC transactions

[Zhi Wang <zhiw@nvidia.com>]

GMC operations such as GSP plugin resource cleanup have no response
payload, but still report success or failure in the response header.

Add a helper that waits for the matching response with a zero payload
limit and converts a nonzero firmware status to EIO.

Co-developed-by: Alok Kumar <alkumar@nvidia.com>
Signed-off-by: Alok Kumar <alkumar@nvidia.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/gpu/nova-core/gsp/cmdq.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/gsp/cmdq.rs b/drivers/gpu/nova-core/gsp/cmdq.rs
index 9fb17e576eb8..891dec5c108a 100644
--- a/drivers/gpu/nova-core/gsp/cmdq.rs
+++ b/drivers/gpu/nova-core/gsp/cmdq.rs
@@ -503,7 +503,6 @@ pub(crate) enum QueuePointers {
 /// Response from a GMC API command.
 pub(crate) struct GmcResponse {
     /// Response status (`NV_STATUS` code). Zero means success.
-    #[expect(dead_code)]
     pub(crate) status: u32,
     /// Response payload copied out of the message queue.
     #[expect(dead_code)]
@@ -652,7 +651,6 @@ pub(crate) fn send_gmc_no_wait(
     ///
     /// The queue stays locked for the complete transaction. A single deadline bounds all queue
     /// elements observed while waiting.
-    #[expect(dead_code)]
     pub(crate) fn send_gmc_and_receive(
         &self,
         command_id: u32,
@@ -736,6 +734,17 @@ pub(crate) fn send_gmc_and_receive_timeout(
         }
     }
 
+    /// Sends a synchronous GMC command and checks its status-only reply.
+    #[expect(dead_code)]
+    pub(crate) fn send_gmc_and_check_status(&self, command_id: u32, payload: &[u8]) -> Result {
+        let response = self.send_gmc_and_receive(command_id, payload, 0)?;
+        if response.status == 0 {
+            Ok(())
+        } else {
+            Err(EIO)
+        }
+    }
+
     /// Waits for an unsolicited GSP event of type `M`, consuming any other event that arrives
     /// first.
     ///