media: pulse8-cec: fix lost cec_transmit_attempt_done() call

commit e5a52a1d upstream.

The periodic PING command could interfere with the result of
a CEC transmit, causing a lost cec_transmit_attempt_done()
call.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: <stable@vger.kernel.org>      # for v4.10 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/media/usb/pulse8-cec/pulse8-cec.c

@@ -121,6 +121,7 @@ struct pulse8 {
 	unsigned int vers;
 	struct completion cmd_done;
 	struct work_struct work;
+	u8 work_result;
 	struct delayed_work ping_eeprom_work;
 	struct cec_msg rx_msg;
 	u8 data[DATA_SIZE];
@@ -142,8 +143,10 @@ static void pulse8_irq_work_handler(struct work_struct *work)
 {
 	struct pulse8 *pulse8 =
 		container_of(work, struct pulse8, work);
+	u8 result = pulse8->work_result;
 
-	switch (pulse8->data[0] & 0x3f) {
+	pulse8->work_result = 0;
+	switch (result & 0x3f) {
 	case MSGCODE_FRAME_DATA:
 		cec_received_msg(pulse8->adap, &pulse8->rx_msg);
 		break;
@@ -177,12 +180,12 @@ static irqreturn_t pulse8_interrupt(struct serio *serio, unsigned char data,
 		pulse8->escape = false;
 	} else if (data == MSGEND) {
 		struct cec_msg *msg = &pulse8->rx_msg;
+		u8 msgcode = pulse8->buf[0];
 
 		if (debug)
 			dev_info(pulse8->dev, "received: %*ph\n",
 				 pulse8->idx, pulse8->buf);
-		pulse8->data[0] = pulse8->buf[0];
-		switch (pulse8->buf[0] & 0x3f) {
+		switch (msgcode & 0x3f) {
 		case MSGCODE_FRAME_START:
 			msg->len = 1;
 			msg->msg[0] = pulse8->buf[1];
@@ -191,14 +194,20 @@ static irqreturn_t pulse8_interrupt(struct serio *serio, unsigned char data,
 			if (msg->len == CEC_MAX_MSG_SIZE)
 				break;
 			msg->msg[msg->len++] = pulse8->buf[1];
-			if (pulse8->buf[0] & MSGCODE_FRAME_EOM)
+			if (msgcode & MSGCODE_FRAME_EOM) {
+				WARN_ON(pulse8->work_result);
+				pulse8->work_result = msgcode;
 				schedule_work(&pulse8->work);
+				break;
+			}
 			break;
 		case MSGCODE_TRANSMIT_SUCCEEDED:
 		case MSGCODE_TRANSMIT_FAILED_LINE:
 		case MSGCODE_TRANSMIT_FAILED_ACK:
 		case MSGCODE_TRANSMIT_FAILED_TIMEOUT_DATA:
 		case MSGCODE_TRANSMIT_FAILED_TIMEOUT_LINE:
+			WARN_ON(pulse8->work_result);
+			pulse8->work_result = msgcode;
 			schedule_work(&pulse8->work);
 			break;
 		case MSGCODE_HIGH_ERROR: