From: Takatoshi Akiyama <takatoshi.akiyama.kj@xxxxxxxxxxxxxxxxxxxxxxxx>
This patch fixes an issue that kernel panic happens when DMA is enabled
and we press enter key while the kernel booting on the serial console.
* An interrupt may occur after sci_request_irq().
* DMA transfer area is initialized by setup_timer() in sci_request_dma()
and used in interrupt.
If an interrupt occurred between sci_request_irq() and setup_timer() in
sci_request_dma(), DMA transfer area has not been initialized yet.
So, this patch changes the order of sci_request_irq() and
sci_request_dma().
Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@xxxxxxxxxxxxxxxxxxxxxxxx>
[Shimoda changes the commit log]
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
This patch is based on the following repo and tag:
- renesas-drivers.git / renesas-drivers-2017-02-21-v4.10 tag
drivers/tty/serial/sh-sci.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 1d6f953..681e469 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1985,11 +1985,13 @@ static int sci_startup(struct uart_port *port)
dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
+ sci_request_dma(port);
+
ret = sci_request_irq(s);
- if (unlikely(ret < 0))
+ if (unlikely(ret < 0)) {
+ sci_free_dma(port);
return ret;
-
- sci_request_dma(port);
+ }
return 0;
}
@@ -2021,8 +2023,8 @@ static void sci_shutdown(struct uart_port *port)
}
#endif
- sci_free_dma(port);
sci_free_irq(s);
+ sci_free_dma(port);
}
static int sci_sck_calc(struct sci_port *s, unsigned int bps,
--
1.9.1
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