Input: zforce_ts - remove unneeded locking

There is no need to have a lock around calls to i2c_master_send() and
i2c_master_recv() as they are not issued concurrently and they are not
sharing any buffers. Also there is no need for command_mutex as all
commands are issued sequentially.

Remove both.

Tested-by: Andreas Kemnade <andreas@kemnade.info> # Tolino Shine2HD
Link: https://lore.kernel.org/r/20240824055047.1706392-7-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/zforce_ts.c b/drivers/input/touchscreen/zforce_ts.c
index a4956f1eebb25959bb17dc76290eec8dde8e75f7..afeafa5899282e99e980035f336e9e9dfef031a2 100644 (file)
--- a/drivers/input/touchscreen/zforce_ts.c
+++ b/drivers/input/touchscreen/zforce_ts.c
@@ -95,9 +95,7 @@ struct zforce_point {
  * @suspending         in the process of going to suspend (don't emit wakeup
  *                     events for commands executed to suspend the device)
  * @suspended          device suspended
- * @access_mutex       serialize i2c-access, to keep multipart reads together
  * @command_done       completion to wait for the command result
- * @command_mutex      serialize commands sent to the ic
  * @command_waiting    the id of the command that is currently waiting
  *                     for a result
  * @command_result     returned result of the command
@@ -123,10 +121,7 @@ struct zforce_ts {
        u16                     version_build;
        u16                     version_rev;
 
-       struct mutex            access_mutex;
-
        struct completion       command_done;
-       struct mutex            command_mutex;
        int                     command_waiting;
        int                     command_result;
 };
@@ -143,9 +138,7 @@ static int zforce_command(struct zforce_ts *ts, u8 cmd)
        buf[1] = 1; /* data size, command only */
        buf[2] = cmd;
 
-       mutex_lock(&ts->access_mutex);
        ret = i2c_master_send(client, &buf[0], ARRAY_SIZE(buf));
-       mutex_unlock(&ts->access_mutex);
        if (ret < 0) {
                dev_err(&client->dev, "i2c send data request error: %d\n", ret);
                return ret;
@@ -169,37 +162,24 @@ static int zforce_send_wait(struct zforce_ts *ts, const char *buf, int len)
        struct i2c_client *client = ts->client;
        int ret;
 
-       ret = mutex_trylock(&ts->command_mutex);
-       if (!ret) {
-               dev_err(&client->dev, "already waiting for a command\n");
-               return -EBUSY;
-       }
-
        dev_dbg(&client->dev, "sending %d bytes for command 0x%x\n",
                buf[1], buf[2]);
 
        ts->command_waiting = buf[2];
 
-       mutex_lock(&ts->access_mutex);
        ret = i2c_master_send(client, buf, len);
-       mutex_unlock(&ts->access_mutex);
        if (ret < 0) {
                dev_err(&client->dev, "i2c send data request error: %d\n", ret);
-               goto unlock;
+               return ret;;
        }
 
        dev_dbg(&client->dev, "waiting for result for command 0x%x\n", buf[2]);
 
-       if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0) {
-               ret = -ETIME;
-               goto unlock;
-       }
+       if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0)
+               return -ETIME;
 
        ret = ts->command_result;
-
-unlock:
-       mutex_unlock(&ts->command_mutex);
-       return ret;
+       return 0;
 }
 
 static int zforce_command_wait(struct zforce_ts *ts, u8 cmd)
@@ -412,41 +392,35 @@ static int zforce_read_packet(struct zforce_ts *ts, u8 *buf)
        struct i2c_client *client = ts->client;
        int ret;
 
-       mutex_lock(&ts->access_mutex);
-
        /* read 2 byte message header */
        ret = i2c_master_recv(client, buf, 2);
        if (ret < 0) {
                dev_err(&client->dev, "error reading header: %d\n", ret);
-               goto unlock;
+               return ret;
        }
 
        if (buf[PAYLOAD_HEADER] != FRAME_START) {
                dev_err(&client->dev, "invalid frame start: %d\n", buf[0]);
-               ret = -EIO;
-               goto unlock;
+               return -EIO;
        }
 
        if (buf[PAYLOAD_LENGTH] == 0) {
                dev_err(&client->dev, "invalid payload length: %d\n",
                        buf[PAYLOAD_LENGTH]);
-               ret = -EIO;
-               goto unlock;
+               return -EIO;
        }
 
        /* read the message */
        ret = i2c_master_recv(client, &buf[PAYLOAD_BODY], buf[PAYLOAD_LENGTH]);
        if (ret < 0) {
                dev_err(&client->dev, "error reading payload: %d\n", ret);
-               goto unlock;
+               return ret;
        }
 
        dev_dbg(&client->dev, "read %d bytes for response command 0x%x\n",
                buf[PAYLOAD_LENGTH], buf[PAYLOAD_BODY]);
 
-unlock:
-       mutex_unlock(&ts->access_mutex);
-       return ret;
+       return 0;
 }
 
 static void zforce_complete(struct zforce_ts *ts, int cmd, int result)
@@ -801,9 +775,6 @@ static int zforce_probe(struct i2c_client *client)
                return -ENOMEM;
        }
 
-       mutex_init(&ts->access_mutex);
-       mutex_init(&ts->command_mutex);
-
        ts->client = client;
        ts->input = input_dev;