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author | James Hogan <james.hogan@imgtec.com> | 2017-03-04 13:09:58 +0000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-03-14 10:48:11 +0800 |
commit | b15bfbe6427712d1b992bf806a6df9c05002a0a4 (patch) | |
tree | 801f606e6e6327804baa0676eed386958a02f7aa | |
parent | 09498087f922bb623b66db9e89c6fd11a3799867 (diff) | |
download | linux-b15bfbe6427712d1b992bf806a6df9c05002a0a4.tar.gz linux-b15bfbe6427712d1b992bf806a6df9c05002a0a4.tar.bz2 linux-b15bfbe6427712d1b992bf806a6df9c05002a0a4.zip |
serial: 8250_dw: Fix breakage when HAVE_CLK=n
Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be
used") recently broke the 8250_dw driver on platforms which don't select
HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the
fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything
is fine but returns (valid) NULL clocks and 0 HZ clock rates.
That 0 rate is written into the uartclk resulting in a crash at boot,
e.g. on Cavium Octeon III based UTM-8 we get something like this:
1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0
...
Call Trace:
...
[<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0
[<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440
[<ffffffff8149c710>] uart_set_options+0xe8/0x190
[<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158
[<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70
[<ffffffff811901a0>] register_console+0x1c8/0x418
[<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0
[<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440
[<ffffffff814aa620>] dw8250_probe+0x388/0x5e8
...
The clock API is defined such that NULL is a valid clock handle so it
wouldn't be right to check explicitly for NULL. Instead treat a
clk_round_rate() return value of 0 as an error which prevents uartclk
being overwritten.
Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-serial@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: bcm-kernel-feedback-list@broadcom.com
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Jason Uy <jason.uy@broadcom.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/tty/serial/8250/8250_dw.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 223ac234ddb2..e65808c482f1 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -267,6 +267,8 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, rate = clk_round_rate(d->clk, baud * 16); if (rate < 0) ret = rate; + else if (rate == 0) + ret = -ENOENT; else ret = clk_set_rate(d->clk, rate); clk_prepare_enable(d->clk); |