diff options
| author | Johan Hovold <johan@kernel.org> | 2021-10-07 15:31:46 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-10-07 16:22:29 +0200 |
| commit | d02b006b29de14968ba4afa998bede0d55469e29 (patch) | |
| tree | 06687a0bff6efa9839ba72b4cd2554d3a19e0a61 /drivers/tty | |
| parent | 32262e2e429cdb31f9e957e997d53458762931b7 (diff) | |
Revert "serial: 8250: Fix reporting real baudrate value in c_ospeed field"
This reverts commit 32262e2e429cdb31f9e957e997d53458762931b7.
The commit in question claims to determine the inverse of
serial8250_get_divisor() but failed to notice that some drivers override
the default implementation using a get_divisor() callback.
This means that the computed line-speed values can be completely wrong
and results in regular TCSETS requests failing (the incorrect values
would also be passed to any overridden set_divisor() callback).
Similarly, it also failed to honour the old (deprecated) ASYNC_SPD_FLAGS
and would break applications relying on those when re-encoding the
actual line speed.
There are also at least two quirks, UART_BUG_QUOT and an OMAP1510
workaround, which were happily ignored and that are now broken.
Finally, even if the offending commit were to be implemented correctly,
this is a new feature and not something which should be backported to
stable.
Cc: Pali Rohár <pali@kernel.org>
Fixes: 32262e2e429c ("serial: 8250: Fix reporting real baudrate value in c_ospeed field")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211007133146.28949-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 17 |
1 files changed, 0 insertions, 17 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index dc6900b2daa8..66374704747e 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2584,19 +2584,6 @@ static unsigned int serial8250_get_divisor(struct uart_port *port, return serial8250_do_get_divisor(port, baud, frac); } -static unsigned int serial8250_compute_baud_rate(struct uart_port *port, - unsigned int quot) -{ - if ((port->flags & UPF_MAGIC_MULTIPLIER) && quot == 0x8001) - return port->uartclk / 4; - else if ((port->flags & UPF_MAGIC_MULTIPLIER) && quot == 0x8002) - return port->uartclk / 8; - else if (port->type == PORT_NPCM) - return DIV_ROUND_CLOSEST(port->uartclk - 2 * (quot + 2), 16 * (quot + 2)); - else - return DIV_ROUND_CLOSEST(port->uartclk, 16 * quot); -} - static unsigned char serial8250_compute_lcr(struct uart_8250_port *up, tcflag_t c_cflag) { @@ -2727,14 +2714,11 @@ void serial8250_update_uartclk(struct uart_port *port, unsigned int uartclk) baud = serial8250_get_baud_rate(port, termios, NULL); quot = serial8250_get_divisor(port, baud, &frac); - baud = serial8250_compute_baud_rate(port, quot); serial8250_rpm_get(up); spin_lock_irqsave(&port->lock, flags); uart_update_timeout(port, termios->c_cflag, baud); - if (tty_termios_baud_rate(termios)) - tty_termios_encode_baud_rate(termios, baud, baud); serial8250_set_divisor(port, baud, quot, frac); serial_port_out(port, UART_LCR, up->lcr); @@ -2766,7 +2750,6 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, baud = serial8250_get_baud_rate(port, termios, old); quot = serial8250_get_divisor(port, baud, &frac); - baud = serial8250_compute_baud_rate(port, quot); /* * Ok, we're now changing the port state. Do it with |