usb: typec: ucsi: Fix completion notifications

OPM                         PPM                         LPM
 |        1.send cmd         |                           |
 |-------------------------->|                           |
 |                           |--                         |
 |                           |  | 2.set busy bit in CCI  |
 |                           |<-                         |
 |      3.notify the OPM     |                           |
 |<--------------------------|                           |
 |                           | 4.send cmd to be executed |
 |                           |-------------------------->|
 |                           |                           |
 |                           |      5.cmd completed      |
 |                           |<--------------------------|
 |                           |                           |
 |                           |--                         |
 |                           |  | 6.set cmd completed    |
 |                           |<-       bit in CCI        |
 |                           |                           |
 |     7.notify the OPM      |                           |
 |<--------------------------|                           |
 |                           |                           |
 |   8.handle notification   |                           |
 |   from point 3, read CCI  |                           |
 |<--------------------------|                           |
 |                           |                           |

When the PPM receives command from the OPM (p.1) it sets the busy bit
in the CCI (p.2), sends notification to the OPM (p.3) and forwards the
command to be executed by the LPM (p.4). When the PPM receives command
completion from the LPM (p.5) it sets command completion bit in the CCI
(p.6) and sends notification to the OPM (p.7). If command execution by
the LPM is fast enough then when the OPM starts handling the notification
from p.3 in p.8 and reads the CCI value it will see command completion bit
set and will call complete(). Then complete() might be called again when
the OPM handles notification from p.7.

This fix replaces test_bit() with test_and_clear_bit()
in ucsi_notify_common() in order to call complete() only
once per request.

This fix also reinitializes completion variable in
ucsi_sync_control_common() before a command is sent.

Fixes: 584e8df ("usb: typec: ucsi: extract common code for command handling")
Cc: stable@vger.kernel.org
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20241203102318.3386345-1-ukaszb@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Łukasz Bartosik

drivers/usb/typec/ucsi/ucsi.c

@@ -46,11 +46,11 @@ void ucsi_notify_common(struct ucsi *ucsi, u32 cci)
 		ucsi_connector_change(ucsi, UCSI_CCI_CONNECTOR(cci));
 
 	if (cci & UCSI_CCI_ACK_COMPLETE &&
-	    test_bit(ACK_PENDING, &ucsi->flags))
+	    test_and_clear_bit(ACK_PENDING, &ucsi->flags))
 		complete(&ucsi->complete);
 
 	if (cci & UCSI_CCI_COMMAND_COMPLETE &&
-	    test_bit(COMMAND_PENDING, &ucsi->flags))
+	    test_and_clear_bit(COMMAND_PENDING, &ucsi->flags))
 		complete(&ucsi->complete);
 }
 EXPORT_SYMBOL_GPL(ucsi_notify_common);
@@ -65,6 +65,8 @@ int ucsi_sync_control_common(struct ucsi *ucsi, u64 command)
 	else
 		set_bit(COMMAND_PENDING, &ucsi->flags);
 
+	reinit_completion(&ucsi->complete);
+
 	ret = ucsi->ops->async_control(ucsi, command);
 	if (ret)
 		goto out_clear_bit;