From 12e9459ddaea698de369701d94e8a941564d773e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Wed, 17 Apr 2024 11:03:28 +0200
Subject: [PATCH] serial: stm32: Reset .throttled state in .startup()
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commit ea2624b5b829b8f93c0dce25721d835969b34faf upstream.
When an UART is opened that still has .throttled set from a previous
open, the RX interrupt is enabled but the irq handler doesn't consider
it. This easily results in a stuck irq with the effect to occupy the CPU
in a tight loop.
So reset the throttle state in .startup() to ensure that RX irqs are
handled.
Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/a784f80d3414f7db723b2ec66efc56e1ad666cbf.1713344161.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/stm32-usart.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 90f83e6fc592..9ef90bb30a47 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1077,6 +1077,7 @@ static int stm32_usart_startup(struct uart_port *port)
val |= USART_CR2_SWAP;
writel_relaxed(val, port->membase + ofs->cr2);
}
+ stm32_port->throttled = false;
/* RX FIFO Flush */
if (ofs->rqr != UNDEF_REG)
--
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