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Commit 55a1c6db authored by Karthikeyan Ramasubramanian's avatar Karthikeyan Ramasubramanian
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tty: serial: msm_geni_serial: Handle the Console RX overflow 



Debug UART does not have flow control lines and that can lead to an
overflow in the RX direction. Keep the RX FIFO watermark to a small
value so that the UART can provide a quicker response and minimize
the overflow. In case of an overflow, update the right statistics that
can be monitored through proc file system. Also insert the TTY_OVERRUN
character to the framework to indicate overflow scenario.

Change-Id: I0b6a6cadcd76a85ac0130efbc7d5b94d9bdbad17
Signed-off-by: default avatarKarthikeyan Ramasubramanian <kramasub@codeaurora.org>
parent 967b6fb1

drivers/tty/serial/msm_geni_serial.c

+8 −2
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ 
} while (0)



#define DMA_RX_BUF_SIZE		(2048)

#define UART_CONSOLE_RX_WM	(2)

struct msm_geni_serial_port {

	struct uart_port uport;

	char name[20];
@@ -1358,6 +1359,7 @@ static irqreturn_t msm_geni_serial_isr(int isr, void *dev) 
	unsigned long flags;

	unsigned int m_irq_en;

	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);

	struct tty_port *tport = &uport->state->port;

	bool drop_rx = false;



	spin_lock_irqsave(&uport->lock, flags);
@@ -1387,7 +1389,8 @@ static irqreturn_t msm_geni_serial_isr(int isr, void *dev) 
	}



	if (s_irq_status & S_RX_FIFO_WR_ERR_EN) {

		uport->icount.buf_overrun++;

		uport->icount.overrun++;

		tty_insert_flip_char(tport, 0, TTY_OVERRUN);

		IPC_LOG_MSG(msm_port->ipc_log_misc,

			"%s.sirq 0x%x buf_overrun:%d\n",

			__func__, s_irq_status, uport->icount.buf_overrun);
@@ -1526,7 +1529,10 @@ static void set_rfr_wm(struct msm_geni_serial_port *port) 
	 * TX WM level at 10% TX_FIFO_DEPTH.

	 */

	port->rx_rfr = port->rx_fifo_depth - 2;

	if (!uart_console(&port->uport))

		port->rx_wm = port->rx_fifo_depth >>  1;

	else

		port->rx_wm = UART_CONSOLE_RX_WM;

	port->tx_wm = 2;

}