mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

serial: 8250_dw: Do not reclock if already at correct rate 

When userspace opens the console, we call set_termios() passing a
termios with the console's configured baud rate. Currently this causes
dw8250_set_termios() to disable and then re-enable the UART clock at
the same frequency as it was originally. This can cause corruption
of any concurrent console output. Fix it by skipping the reclocking
if we are already at the correct rate.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Fixes: 4e26b134bd ("serial: 8250_dw: clock rate handling for all ACPI platforms")
Cc: stable@vger.kernel.org
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240222192635.1050502-1-pcc@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Collingbourne 2024-02-22 11:26:34 -08:00 committed by Greg Kroah-Hartman
parent 672448ccf9
commit e5d6bd25f9
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/tty/serial/8250/8250_dw.c
View File

@ -357,9 +357,9 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
long rate;
int ret;
clk_disable_unprepare(d->clk);
rate = clk_round_rate(d->clk, newrate);
if (rate > 0) {
if (rate > 0 && p->uartclk != rate) {
clk_disable_unprepare(d->clk);
/*
* Note that any clock-notifer worker will block in
* serial8250_update_uartclk() until we are done.
@ -367,8 +367,8 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
ret = clk_set_rate(d->clk, newrate);
if (!ret)
p->uartclk = rate;
clk_prepare_enable(d->clk);
}
clk_prepare_enable(d->clk);
dw8250_do_set_termios(p, termios, old);
}