drm/panthor: Always wait after sending a command to an AS

There's currently no situation where we want to issue a command to an
AS and not wait for this command to complete. The wait is either
explicitly done (LOCK, UNLOCK) or it's missing (UPDATE). So let's
turn write_cmd() into as_send_cmd_and_wait() that has the wait after
a command is sent.

v2:
- New patch

v3:
- Collect R-b

v4:
- No changes

Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20251128084841.3804658-2-boris.brezillon@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 8818d6a8d93e272b729687395f3977ebed98e7a9..f59331f89b33ca2fe5c8a2f08f2ea356b32924b8 100644 (file)
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -524,27 +524,29 @@ static int wait_ready(struct panthor_device *ptdev, u32 as_nr)
        return ret;
 }
 
-static int write_cmd(struct panthor_device *ptdev, u32 as_nr, u32 cmd)
+static int as_send_cmd_and_wait(struct panthor_device *ptdev, u32 as_nr, u32 cmd)
 {
        int status;
 
        /* write AS_COMMAND when MMU is ready to accept another command */
        status = wait_ready(ptdev, as_nr);
-       if (!status)
+       if (!status) {
                gpu_write(ptdev, AS_COMMAND(as_nr), cmd);
+               status = wait_ready(ptdev, as_nr);
+       }
 
        return status;
 }
 
-static void lock_region(struct panthor_device *ptdev, u32 as_nr,
-                       u64 region_start, u64 size)
+static int lock_region(struct panthor_device *ptdev, u32 as_nr,
+                      u64 region_start, u64 size)
 {
        u8 region_width;
        u64 region;
        u64 region_end = region_start + size;
 
        if (!size)
-               return;
+               return 0;
 
        /*
         * The locked region is a naturally aligned power of 2 block encoded as
@@ -567,7 +569,7 @@ static void lock_region(struct panthor_device *ptdev, u32 as_nr,
 
        /* Lock the region that needs to be updated */
        gpu_write64(ptdev, AS_LOCKADDR(as_nr), region);
-       write_cmd(ptdev, as_nr, AS_COMMAND_LOCK);
+       return as_send_cmd_and_wait(ptdev, as_nr, AS_COMMAND_LOCK);
 }
 
 static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
@@ -600,9 +602,7 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
         * power it up
         */
 
-       lock_region(ptdev, as_nr, iova, size);
-
-       ret = wait_ready(ptdev, as_nr);
+       ret = lock_region(ptdev, as_nr, iova, size);
        if (ret)
                return ret;
 
@@ -615,10 +615,7 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
         * at the end of the GPU_CONTROL cache flush command, unlike
         * AS_COMMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT.
         */
-       write_cmd(ptdev, as_nr, AS_COMMAND_UNLOCK);
-
-       /* Wait for the unlock command to complete */
-       return wait_ready(ptdev, as_nr);
+       return as_send_cmd_and_wait(ptdev, as_nr, AS_COMMAND_UNLOCK);
 }
 
 static int mmu_hw_do_operation(struct panthor_vm *vm,
@@ -647,7 +644,7 @@ static int panthor_mmu_as_enable(struct panthor_device *ptdev, u32 as_nr,
        gpu_write64(ptdev, AS_MEMATTR(as_nr), memattr);
        gpu_write64(ptdev, AS_TRANSCFG(as_nr), transcfg);
 
-       return write_cmd(ptdev, as_nr, AS_COMMAND_UPDATE);
+       return as_send_cmd_and_wait(ptdev, as_nr, AS_COMMAND_UPDATE);
 }
 
 static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr)
@@ -662,7 +659,7 @@ static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr)
        gpu_write64(ptdev, AS_MEMATTR(as_nr), 0);
        gpu_write64(ptdev, AS_TRANSCFG(as_nr), AS_TRANSCFG_ADRMODE_UNMAPPED);
 
-       return write_cmd(ptdev, as_nr, AS_COMMAND_UPDATE);
+       return as_send_cmd_and_wait(ptdev, as_nr, AS_COMMAND_UPDATE);
 }
 
 static u32 panthor_mmu_fault_mask(struct panthor_device *ptdev, u32 value)