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

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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>
This commit is contained in:
Matthias Schiffer 2020-05-28 17:47:47 +02:00 committed by Greg Kroah-Hartman
parent 423d9118c6
commit d1d996afbd
1 changed files with 2 additions and 0 deletions
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2
drivers/tty/serial/imx.c
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@ -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;
}