Patch "media: tegra-cec: reset rx_buf_cnt when start bit detected" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

media: tegra-cec: reset rx_buf_cnt when start bit detected

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
media-tegra-cec-reset-rx_buf_cnt-when-start-bit-detected.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Hans Verkuil <[email protected]>
Date: Wed, 28 Feb 2018 05:47:07 -0500
Subject: media: tegra-cec: reset rx_buf_cnt when start bit detected

From: Hans Verkuil <[email protected]>

commit e113d65ae417ae6d9be229649b81d404c47ade79 upstream.

If a start bit is detected, then reset the receive buffer counter to 0.

This ensures that no stale data is in the buffer if a message is broken off midstream due to e.g. a Low Drive condition and then retransmitted.

The only Rx interrupts we need to listen to are RX_REGISTER_FULL (i.e. a valid byte was received) and RX_START_BIT_DETECTED (i.e. a new message starts and we need to reset the counter).

---
 drivers/media/platform/tegra-cec/tegra_cec.c |   17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

@@ -172,16 +172,13 @@ static irqreturn_t tegra_cec_irq_handler
 		}
 	}
 
-	if (status & (TEGRA_CEC_INT_STAT_RX_REGISTER_OVERRUN |
-		      TEGRA_CEC_INT_STAT_RX_BUS_ANOMALY_DETECTED |
-		      TEGRA_CEC_INT_STAT_RX_START_BIT_DETECTED |
-		      TEGRA_CEC_INT_STAT_RX_BUS_ERROR_DETECTED)) {
+	if (status & TEGRA_CEC_INT_STAT_RX_START_BIT_DETECTED) {
 		cec_write(cec, TEGRA_CEC_INT_STAT,
-			  (TEGRA_CEC_INT_STAT_RX_REGISTER_OVERRUN |
-			   TEGRA_CEC_INT_STAT_RX_BUS_ANOMALY_DETECTED |
-			   TEGRA_CEC_INT_STAT_RX_START_BIT_DETECTED |
-			   TEGRA_CEC_INT_STAT_RX_BUS_ERROR_DETECTED));
-	} else if (status & TEGRA_CEC_INT_STAT_RX_REGISTER_FULL) {
+			  TEGRA_CEC_INT_STAT_RX_START_BIT_DETECTED);
+		cec->rx_done = false;
+		cec->rx_buf_cnt = 0;
+	}
+	if (status & TEGRA_CEC_INT_STAT_RX_REGISTER_FULL) {
 		u32 v;
 
 		cec_write(cec, TEGRA_CEC_INT_STAT,

@@ -255,7 +252,7 @@ static int tegra_cec_adap_enable(struct
 		  TEGRA_CEC_INT_MASK_TX_BUS_ANOMALY_DETECTED |
 		  TEGRA_CEC_INT_MASK_TX_FRAME_TRANSMITTED |
 		  TEGRA_CEC_INT_MASK_RX_REGISTER_FULL |
-		  TEGRA_CEC_INT_MASK_RX_REGISTER_OVERRUN);
+		  TEGRA_CEC_INT_MASK_RX_START_BIT_DETECTED);
 
 	cec_write(cec, TEGRA_CEC_HW_CONTROL, TEGRA_CEC_HWCTRL_TX_RX_MODE);
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/media-tegra-cec-reset-rx_buf_cnt-when-start-bit-detected.patch