[tty-next] tty: serial: imx: clear Ageing Timer Interrupt in handler

Message ID 20200528154747.14201-1-matthias.schiffer@ew.tq-group.com
State New
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Series
  • [tty-next] tty: serial: imx: clear Ageing Timer Interrupt in handler
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Commit Message

Matthias Schiffer May 28, 2020, 3:47 p.m.
The AGTIM flag must be cleared explicitly, otherwise the IRQ handler
will be called in an endless loop.

Fortunately, this issue currently doesn't affect mainline kernels in
practice, as the the RX FIFO trigger level is set to 1 in UFCR. When
setting the trigger level to a higher number, the issue is trivially
reproducible by any RX without DMA that doesn't fill the FIFO up to the
configured level.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
---
 drivers/tty/serial/imx.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 6b078e395931..1265e8d86d8a 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -909,6 +909,8 @@  static irqreturn_t imx_uart_int(int irq, void *dev_id)
 		usr2 &= ~USR2_ORE;
 
 	if (usr1 & (USR1_RRDY | USR1_AGTIM)) {
+		imx_uart_writel(sport, USR1_AGTIM, USR1);
+
 		__imx_uart_rxint(irq, dev_id);
 		ret = IRQ_HANDLED;
 	}