[PATCH v1 0/7] serial: imx: work-around for hardware RX flood, and then isr improvements

[Sergey Organov <sorganov@gmail.com>]

These series contain a work-around for hardware RX flood in first 2
commits, and then further cleanups and optimizations of the receive IRQ
handler.

WARNING: the flood fix is extensively tested with older version of the
kernel with DMA turned off. The DMA path is tested only a bit, as DMA has
receive problems on my kernel version.

Changes in v1:

  * Missing braces fixed.

  * Withdrawn patch optimizing imx_uart_readl() -> readl(), on request of
    Uwe Kleine-König.

Sergey Organov (7):
  serial: imx: factor-out common code to imx_uart_soft_reset()
  serial: imx: work-around for hardware RX flood
  serial: imx: do not sysrq broken chars
  serial: imx: do not break from FIFO reading loop prematurely
  serial: imx: remove redundant USR2 read from FIFO reading loop
  serial: imx: stop using USR2 in FIFO reading loop
  serial: imx: refine local variables in rxint()

 drivers/tty/serial/imx.c | 225 ++++++++++++++++++++++++---------------
 1 file changed, 140 insertions(+), 85 deletions(-)

Interdiff against v0:
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 45327ff6dd14..447b9060d9df 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -889,15 +889,14 @@ static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
 	struct tty_port *port = &sport->port.state->port;
-	typeof(sport->port.membase) membase = sport->port.membase;
 	u32 usr2, rx;
 
 	/* If we received something, check for 0xff flood */
-	usr2 = readl(membase + USR2);
+	usr2 = imx_uart_readl(sport, USR2);
 	if (usr2 & USR2_RDR)
 		imx_uart_check_flood(sport, usr2);
 
-	while ((rx = readl(membase + URXD0)) & URXD_CHARRDY) {
+	while ((rx = imx_uart_readl(sport, URXD0)) & URXD_CHARRDY) {
 		unsigned int flg = TTY_NORMAL;
 		sport->port.icount.rx++;
 
@@ -929,8 +928,9 @@ static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
 				flg = TTY_OVERRUN;
 
 			sport->port.sysrq = 0;
-		} else if (uart_handle_sysrq_char(&sport->port, (unsigned char)rx))
+		} else if (uart_handle_sysrq_char(&sport->port, (unsigned char)rx)) {
 			continue;
+		}
 
 		if (sport->port.ignore_status_mask & URXD_DUMMY_READ)
 			continue;
-- 
2.30.1