[PATCH] staging: pi433: add descriptions for mutex locks

[Valentin Vidic]

Removes TODO for tx_fifo_lock as tx_fifo is modified from
both pi433_tx_thread and pi433_write.

Fixes checkpatch warning:

  CHECK: struct mutex definition without comment

Signed-off-by: Valentin Vidic <valentin.vi...@carnet.hr>
---
 drivers/staging/pi433/pi433_if.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c
index d1e0ddbc79ce..f6f106a3ff8e 100644
--- a/drivers/staging/pi433/pi433_if.c
+++ b/drivers/staging/pi433/pi433_if.c
@@ -87,7 +87,7 @@ struct pi433_device {
 
        /* tx related values */
        STRUCT_KFIFO_REC_1(MSG_FIFO_SIZE) tx_fifo;
-       struct mutex            tx_fifo_lock; // TODO: check, whether necessary 
or obsolete
+       struct mutex            tx_fifo_lock; /* serialize access to tx_fifo */
        struct task_struct      *tx_task_struct;
        wait_queue_head_t       tx_wait_queue;
        u8                      free_in_fifo;
@@ -100,7 +100,7 @@ struct pi433_device {
        u32                     rx_bytes_to_drop;
        u32                     rx_bytes_dropped;
        unsigned int            rx_position;
-       struct mutex            rx_lock;
+       struct mutex            rx_lock; /* serialize read requests */
        wait_queue_head_t       rx_wait_queue;
 
        /* fifo wait queue */
-- 
2.16.2