linux console设置波特率115200，逻辑分析仪实测为107142，，开机打印信息如下：
[ 0.199149] Serial: 8250/16550 driver, 5 ports, IRQ sharing disabled
[ 0.201430] console [ttyS0] disabled
[ 0.201514] ff0a0000.serial: ttyS0 at MMIO 0xff0a0000 (irq = 10, base_baud = 1500000) is a 16550A
[ 0.201693] clk_uart0_frac parent_rate(24000000) is low than rate(3686400)*20, fractional div is not allowed
[ 0.201789] clk_uart0_frac parent_rate(24000000) is low than rate(3760128)*20, fractional div is not allowed
[ 0.201811] dw-apb-uart ff0a0000.serial: set rate:3686400, but get rate:3428572
[ 1.240605] console [ttyS0] enabled
是不是因为UART0时钟除以115200波特率商不是整数导致的？如果换个其他波特率的话，应该能得到准确波特率
不过如果希望继续用115200的话，，请问应该怎么设置？
离线
问题解决了，，解决方法：
将 drivers/tty/serial/8250/8250_dw.c 中函数 dw8250_set_termios() 里面的
#ifdef CONFIG_ARCH_ROCKCHIP
if ((baud * 16) <= 4000000) {
/*
* Make sure uart sclk is high enough
*/
div = 4000000 / baud / 16;
rate = baud * 16 * div;
} else {
rate = baud * 16;
}
ret = clk_set_rate(d->clk, rate);
rate_temp = clk_get_rate(d->clk);
diff = rate * 20 / 1000;
/*
* If rate_temp is not equal to rate, is means fractional frequency
* division is failed. Then use Integer frequency division, and
* the buad rate error must be under -+2%
*/
if ((rate_temp < rate) && ((rate - rate_temp) > diff)) {
ret = clk_set_rate(d->clk, rate + diff);
rate_temp = clk_get_rate(d->clk);
if ((rate_temp < rate) && ((rate - rate_temp) > diff))
dev_info(p->dev, "set rate:%d, but get rate:%d\n",
rate, rate_temp);
else if ((rate < rate_temp) && ((rate_temp - rate) > diff))
dev_info(p->dev, "set rate:%d, but get rate:%d\n",
rate, rate_temp);
}
#else替换为：
#ifdef CONFIG_ARCH_ROCKCHIP
rate = clk_get_rate(clk_get_parent(d->clk));
ret = clk_set_rate(d->clk, rate);
#else离线