Commit d1d996af authored May 28, 2020 by Matthias Schiffer Committed by Greg Kroah-Hartman May 29, 2020

tty: serial: imx: clear Ageing Timer Interrupt in handler

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>
Link: https://lore.kernel.org/r/20200528154747.14201-1-matthias.schiffer@ew.tq-group.com

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 423d9118

drivers/tty/serial/imx.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}