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serial: qcom_geni_serial: Finish supporting sysrq

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The geni serial driver already had some sysrq code in it, but since
SUPPORT_SYSRQ wasn't defined the code didn't do anything useful.
Let's make it useful by adding that define using the same formula
found in other serial drivers.

In order to prevent deadlock, we'll take a page from the
'msm_serial.c' where the spinlock is released around
uart_handle_sysrq_char().  This seemed better than copying from
'8250_port.c' where we skip locking in the console_write function
since the '8250_port.c' method can cause lockdep warnings when
dropping into kgdb.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Douglas Anderson 2018-10-30 15:11:03 -07:00 committed by Greg Kroah-Hartman
parent 6d11023c34
commit babeca8584
1 changed files with 7 additions and 0 deletions
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7
drivers/tty/serial/qcom_geni_serial.c
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@ -1,6 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
#if defined(CONFIG_SERIAL_QCOM_GENI_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
# define SUPPORT_SYSRQ
#endif
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/io.h>
@ -493,7 +497,10 @@ static int handle_rx_console(struct uart_port *uport, u32 bytes, bool drop)
continue;
}
spin_unlock(&uport->lock);
sysrq = uart_handle_sysrq_char(uport, buf[c]);
spin_lock(&uport->lock);
if (!sysrq)
tty_insert_flip_char(tport, buf[c], TTY_NORMAL);
}