From de89e43ada08a8409dbdadb5728bee2e1c89661a Mon Sep 17 00:00:00 2001
From: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
Date: Thu, 10 Sep 2020 13:29:46 +0530
Subject: [PATCH] serial: msm_geni_serial: Add delay for rx invalid transfer

Check for RX data in rx buffer for faulty transfer and add
delay of 2 msecs delay in order for dma rx transfer
to be actually completed.

Also dump required qup registers when the uart dma rx data is
seen as all zeros.

Change-Id: Ifaa0cb7d22b8419ffacfee7212b0a28ed8ebf2a1
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
---
 drivers/tty/serial/msm_geni_serial.c | 38 ++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/tty/serial/msm_geni_serial.c b/drivers/tty/serial/msm_geni_serial.c
index e9488f2d0822..d449d54e03cd 100644
--- a/drivers/tty/serial/msm_geni_serial.c
+++ b/drivers/tty/serial/msm_geni_serial.c
@@ -1686,6 +1686,40 @@ exit_handle_tx:
 	return 0;
 }
 
+static void check_rx_buf(char *buf, struct uart_port *uport, int size)
+{
+	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);
+	unsigned int rx_data;
+	bool fault = false;
+
+	rx_data = *(u32 *)buf;
+	/* check for first 4 bytes of RX data for faulty zero pattern */
+	if (rx_data == 0x0) {
+		if (size <= 4) {
+			fault = true;
+		} else {
+			/*
+			 * check for last 4 bytes of data in RX buffer for
+			 * faulty pattern
+			 */
+			if (memcmp(buf+(size-4), "\x0\x0\x0\x0", 4) == 0)
+				fault = true;
+		}
+
+		if (fault) {
+			IPC_LOG_MSG(msm_port->ipc_log_rx,
+				"RX Invalid packet %s\n", __func__);
+			geni_se_dump_dbg_regs(&msm_port->serial_rsc,
+				uport->membase, msm_port->ipc_log_misc);
+			/*
+			 * Add 2 msecs delay in order for dma rx transfer
+			 * to be actually completed.
+			 */
+			udelay(2000);
+		}
+	}
+}
+
 static int msm_geni_serial_handle_dma_rx(struct uart_port *uport, bool drop_rx)
 {
 	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);
@@ -1714,6 +1748,10 @@ static int msm_geni_serial_handle_dma_rx(struct uart_port *uport, bool drop_rx)
 					__func__, rx_bytes);
 		goto exit_handle_dma_rx;
 	}
+
+	/* Check RX buffer data for faulty pattern*/
+	check_rx_buf((char *)msm_port->rx_buf, uport, rx_bytes);
+
 	if (drop_rx)
 		goto exit_handle_dma_rx;