[PATCH] drm/panthor: Remove dead code in mmu_hw_do_operation_locked

[PATCH] drm/panthor: Remove dead code in mmu_hw_do_operation_locked

[Steven Price]

The only callers to mmu_hw_do_operation_locked() pass an 'op' of either
AS_COMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT. So remove the code paths
that test for other operations and add a drm_WARN_ON() to catch the
posibility of others appearing the future.

Suggested-by: Daniel Stone <daniel@fooishbar.org>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 367c89aca558..b16f44aec725 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -612,17 +612,12 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
 	 * power it up
 	 */
 
-	if (op != AS_COMMAND_UNLOCK)
-		lock_region(ptdev, as_nr, iova, size);
+	drm_WARN_ON(&ptdev->base,
+		    op != AS_COMMAND_FLUSH_MEM && op != AS_COMMAND_FLUSH_PT);
 
-	if (op == AS_COMMAND_FLUSH_MEM || op == AS_COMMAND_FLUSH_PT)
-		return mmu_hw_do_flush_on_gpu_ctrl(ptdev, as_nr, op);
+	lock_region(ptdev, as_nr, iova, size);
 
-	/* Run the MMU operation */
-	write_cmd(ptdev, as_nr, op);
-
-	/* Wait for the flush to complete */
-	return wait_ready(ptdev, as_nr);
+	return mmu_hw_do_flush_on_gpu_ctrl(ptdev, as_nr, op);
 }
 
 static int mmu_hw_do_operation(struct panthor_vm *vm,
-- 
2.39.5

Re: [PATCH] drm/panthor: Remove dead code in mmu_hw_do_operation_locked

[Daniel Stone]

Hi Steven,

On Fri, 15 Aug 2025 at 11:25, Steven Price <steven.price@arm.com> wrote:
> The only callers to mmu_hw_do_operation_locked() pass an 'op' of either
> AS_COMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT. So remove the code paths
> that test for other operations and add a drm_WARN_ON() to catch the
> posibility of others appearing the future.

Thanks! I think it would make sense to also inline
mmu_hw_do_flush_on_gpu_ctrl() here though.

Cheers,
Daniel

Re: [PATCH] drm/panthor: Remove dead code in mmu_hw_do_operation_locked

[Steven Price]

On 15/08/2025 12:17, Daniel Stone wrote:
> Hi Steven,
> 
> On Fri, 15 Aug 2025 at 11:25, Steven Price <steven.price@arm.com> wrote:
>> The only callers to mmu_hw_do_operation_locked() pass an 'op' of either
>> AS_COMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT. So remove the code paths
>> that test for other operations and add a drm_WARN_ON() to catch the
>> posibility of others appearing the future.
> 
> Thanks! I think it would make sense to also inline
> mmu_hw_do_flush_on_gpu_ctrl() here though.

True, I'll have a go at a proper rewrite of that function to make it
more coherent.

Thanks,
Steve