From: Bjorn Andersson bjorn.andersson@linaro.org
commit 8c9b3caab3ac26db1da00b8117901640c55a69dd upstream.
It's possible that the interrupt handler for the UCSI driver signals a connector changes after the handler clears the PENDING bit, but before it has sent the acknowledge request. The result is that the handler is invoked yet again, to ack the same connector change.
At least some versions of the Qualcomm UCSI firmware will not handle the second - "spurious" - acknowledgment gracefully. So make sure to not clear the pending flag until the change is acknowledged.
Any connector changes coming in after the acknowledgment, that would have the pending flag incorrectly cleared, would afaict be covered by the subsequent connector status check.
Fixes: 217504a05532 ("usb: typec: ucsi: Work around PPM losing change information") Cc: stable stable@vger.kernel.org Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com Acked-By: Benjamin Berg bberg@redhat.com Signed-off-by: Bjorn Andersson bjorn.andersson@linaro.org Link: https://lore.kernel.org/r/20210516040953.622409-1-bjorn.andersson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/typec/ucsi/ucsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -717,8 +717,8 @@ static void ucsi_handle_connector_change ucsi_send_command(con->ucsi, command, NULL, 0);
/* 3. ACK connector change */ - clear_bit(EVENT_PENDING, &ucsi->flags); ret = ucsi_acknowledge_connector_change(ucsi); + clear_bit(EVENT_PENDING, &ucsi->flags); if (ret) { dev_err(ucsi->dev, "%s: ACK failed (%d)", __func__, ret); goto out_unlock;