| Message ID | 7d5b04da13d89b8708b9543a0b125f2b6062a77b.1667977259.git.lukas@wunner.de |
|---|---|
| State | New |
| Headers | show |
| Series | [tty-next] serial: 8250: 8250_omap: Fix calculation of RS485 delays | expand |
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 1dd8c5b..734f092 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -824,7 +824,7 @@ static int omap8250_rs485_config(struct uart_port *port, * of the AM65 TRM: https://www.ti.com/lit/ug/spruid7e/spruid7e.pdf */ if (priv->quot) { - if (priv->mdr1 & UART_OMAP_MDR1_16X_MODE) + if (priv->mdr1 == UART_OMAP_MDR1_16X_MODE) baud = port->uartclk / (16 * priv->quot); else baud = port->uartclk / (13 * priv->quot);
Commit 801954d1210a ("serial: 8250: 8250_omap: Support native RS485") calculates RS485 delays from the baudrate. The baudrate is generated with either a 16x or 13x divisor. The divisor is set in the Mode Definition Register 1 (MDR1). The commit erroneously assumes that the register stores the divisor as a bitmask and uses a logical AND to differentiate between 16x and 13x divisors. However the divisor is really stored as a 3-bit mode (see lines 363ff in include/uapi/linux/serial_reg.h). The logical AND operation is performed with UART_OMAP_MDR1_16X_MODE, which is defined as 0x0 and hence yields false. So the commit always assumes a 13x divisor. Fix by using an equal comparison. This works because we never set any of the other 5 bits in the register. (They pertain to IrDA mode, which is not supported by the driver). Fixes: 801954d1210a ("serial: 8250: 8250_omap: Support native RS485") Link: https://lore.kernel.org/linux-serial/202211070440.8hWunFUN-lkp@intel.com/ Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <error27@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> --- drivers/tty/serial/8250/8250_omap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)