On 25/04/2019 10:41, Long Cheng wrote: > Add SW and HW follow control function. Can you please explain a bit more what you are doing in this patch. You change the setting of the registers for different baud rates. Please elaborate what is happening there. > > Signed-off-by: Long Cheng <long.cheng@xxxxxxxxxxxx> > --- > drivers/tty/serial/8250/8250_mtk.c | 60 ++++++++++++++++++++++-------------- > 1 file changed, 37 insertions(+), 23 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c > index c1fdbc0..959fd85 100644 > --- a/drivers/tty/serial/8250/8250_mtk.c > +++ b/drivers/tty/serial/8250/8250_mtk.c > @@ -21,12 +21,14 @@ > > #include "8250.h" > > -#define UART_MTK_HIGHS 0x09 /* Highspeed register */ > -#define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */ > -#define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */ > +#define MTK_UART_HIGHS 0x09 /* Highspeed register */ > +#define MTK_UART_SAMPLE_COUNT 0x0a /* Sample count register */ > +#define MTK_UART_SAMPLE_POINT 0x0b /* Sample point register */ Rename looks good to me. But I'd prefer to have it in a separate patch. > #define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */ > - > #define MTK_UART_DMA_EN 0x13 /* DMA Enable register */ > +#define MTK_UART_RXTRI_AD 0x14 /* RX Trigger address */ > +#define MTK_UART_FRACDIV_L 0x15 /* Fractional divider LSB address */ > +#define MTK_UART_FRACDIV_M 0x16 /* Fractional divider MSB address */ > #define MTK_UART_DMA_EN_TX 0x2 > #define MTK_UART_DMA_EN_RX 0x5 > > @@ -46,6 +48,7 @@ enum dma_rx_status { > struct mtk8250_data { > int line; > unsigned int rx_pos; > + unsigned int clk_count; What is that for, not used in this patch. > struct clk *uart_clk; > struct clk *bus_clk; > struct uart_8250_dma *dma; > @@ -196,9 +199,15 @@ static void mtk8250_shutdown(struct uart_port *port) > mtk8250_set_termios(struct uart_port *port, struct ktermios *termios, > struct ktermios *old) > { > + unsigned short fraction_L_mapping[] = { > + 0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF > + }; > + unsigned short fraction_M_mapping[] = { > + 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3 > + }; > struct uart_8250_port *up = up_to_u8250p(port); > + unsigned int baud, quot, fraction; > unsigned long flags; > - unsigned int baud, quot; > > #ifdef CONFIG_SERIAL_8250_DMA > if (up->dma) { > @@ -214,7 +223,7 @@ static void mtk8250_shutdown(struct uart_port *port) > serial8250_do_set_termios(port, termios, old); > > /* > - * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS) > + * Mediatek UARTs use an extra highspeed register (MTK_UART_HIGHS) > * > * We need to recalcualte the quot register, as the claculation depends > * on the vaule in the highspeed register. > @@ -230,18 +239,11 @@ static void mtk8250_shutdown(struct uart_port *port) > port->uartclk / 16 / UART_DIV_MAX, > port->uartclk); > > - if (baud <= 115200) { > - serial_port_out(port, UART_MTK_HIGHS, 0x0); > + if (baud < 115200) { > + serial_port_out(port, MTK_UART_HIGHS, 0x0); > quot = uart_get_divisor(port, baud); > - } else if (baud <= 576000) { > - serial_port_out(port, UART_MTK_HIGHS, 0x2); > - > - /* Set to next lower baudrate supported */ > - if ((baud == 500000) || (baud == 576000)) > - baud = 460800; > - quot = DIV_ROUND_UP(port->uartclk, 4 * baud); So we allow now also these baud rates? Then you have to update the comment as well. Regards, Matthias > } else { > - serial_port_out(port, UART_MTK_HIGHS, 0x3); > + serial_port_out(port, MTK_UART_HIGHS, 0x3); > quot = DIV_ROUND_UP(port->uartclk, 256 * baud); > } > > @@ -258,17 +260,29 @@ static void mtk8250_shutdown(struct uart_port *port) > /* reset DLAB */ > serial_port_out(port, UART_LCR, up->lcr); > > - if (baud > 460800) { > + if (baud >= 115200) { > unsigned int tmp; > > - tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud); > - serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1); > - serial_port_out(port, UART_MTK_SAMPLE_POINT, > - (tmp - 2) >> 1); > + tmp = (port->uartclk / (baud * quot)) - 1; > + serial_port_out(port, MTK_UART_SAMPLE_COUNT, tmp); > + serial_port_out(port, MTK_UART_SAMPLE_POINT, > + (tmp >> 1) - 1); > + > + /*count fraction to set fractoin register */ > + fraction = ((port->uartclk * 100) / baud / quot) % 100; > + fraction = DIV_ROUND_CLOSEST(fraction, 10); > + serial_port_out(port, MTK_UART_FRACDIV_L, > + fraction_L_mapping[fraction]); > + serial_port_out(port, MTK_UART_FRACDIV_M, > + fraction_M_mapping[fraction]); > } else { > - serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00); > - serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff); > + serial_port_out(port, MTK_UART_SAMPLE_COUNT, 0x00); > + serial_port_out(port, MTK_UART_SAMPLE_POINT, 0xff); > + serial_port_out(port, MTK_UART_FRACDIV_L, 0x00); > + serial_port_out(port, MTK_UART_FRACDIV_M, 0x00); > } > + if (uart_console(port)) > + up->port.cons->cflag = termios->c_cflag; > > spin_unlock_irqrestore(&port->lock, flags); > /* Don't rewrite B0 */ >