Input: libps2 - rework handling of command response

It is not entirely correct that libps2 sets PS2_FLAG_CMD1 after
the device acknowledges each byte sent to the device by the host.
Rework the code so that PS2_FLAG_CMD1 and PS2_FLAG_CMD are set only once,
at the beginning of PS/2 command execution.

Reviewed-by: Raul E Rangel <rrangel@chromium.org>
Link: https://lore.kernel.org/r/20230511185252.386941-4-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 399cda0..d09450e 100644 (file)
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -247,14 +247,19 @@ int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
 
        serio_pause_rx(ps2dev->serio);
 
+       /* Some mice do not ACK the "get ID" command, prepare to handle this. */
        ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
        ps2dev->cmdcnt = receive;
-       if (receive && param)
-               for (i = 0; i < receive; i++)
-                       ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+       if (receive) {
+               /* Indicate that we expect response to the command. */
+               ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
+               if (param)
+                       for (i = 0; i < receive; i++)
+                               ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+       }
 
        /*
-        * Some devices (Synaptics) peform the reset before
+        * Some devices (Synaptics) perform the reset before
         * ACKing the reset command, and so it can take a long
         * time before the ACK arrives.
         */
@@ -434,11 +439,8 @@ bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
                return true;
        }
 
-       if (!ps2dev->nak) {
+       if (!ps2dev->nak)
                ps2dev->flags &= ~PS2_FLAG_NAK;
-               if (ps2dev->cmdcnt)
-                       ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
-       }
 
        ps2dev->flags &= ~PS2_FLAG_ACK;
        wake_up(&ps2dev->wait);