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Subject[PATCH 04/14] serial: tegra: protect IER against LCR.DLAB
Date
From: Ahung Cheng <ahcheng@nvidia.com>

The IER and DLH registers occupy the same address space, selected by
the LCR.DLAB bit. Hence, add port lock to protect IER when LCR.DLAB bit
is set.

Signed-off-by: Ahung Cheng <ahcheng@nvidia.com>
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
---
drivers/tty/serial/serial-tegra.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index d908465..ae7225c 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -296,6 +296,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
unsigned long rate;
unsigned int divisor;
unsigned long lcr;
+ unsigned long flags;
int ret;

if (tup->current_baud == baud)
@@ -315,6 +316,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
}

+ spin_lock_irqsave(&tup->uport.lock, flags);
lcr = tup->lcr_shadow;
lcr |= UART_LCR_DLAB;
tegra_uart_write(tup, lcr, UART_LCR);
@@ -327,6 +329,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)

/* Dummy read to ensure the write is posted */
tegra_uart_read(tup, UART_SCR);
+ spin_unlock_irqrestore(&tup->uport.lock, flags);

tup->current_baud = baud;

--
2.7.4
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