Hi Simon,
On 12/04/2018 04:55 AM, Simon Goldschmidt wrote:
> This reverts commit 6f57c34473d37b8da5e6a3764d0d377d748aeef1 since it
> does not seem to work at least on rk3399.
>
> The Rockchip Technical Reference Manual (TRM) for the rk3399 says the baud
> rate prescaler register is readable only when USR[0] is zero. Since this
> bit is defined as "reserved" in the socfpga cylcone5 TRM, let's rather
> drop this than making the ns16550 debug uart more platform specific.
>
> Reported-by: Roosen Henri <henri.roo...@ginzinger.com>
> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschm...@gmail.com>
Reviewed-by: Kever Yang <kever.y...@rock-chips.com>
Thanks,
- Kever
> ---
>
> drivers/serial/ns16550.c | 18 ++----------------
> 1 file changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> index f21c240e64..25b9d17243 100644
> --- a/drivers/serial/ns16550.c
> +++ b/drivers/serial/ns16550.c
> @@ -272,26 +272,12 @@ static inline void _debug_uart_init(void)
> serial_dout(&com_port->lcr, UART_LCRVAL);
> }
>
> -static inline int NS16550_read_baud_divisor(struct NS16550 *com_port)
> -{
> - int ret;
> -
> - serial_dout(&com_port->lcr, UART_LCR_BKSE | UART_LCRVAL);
> - ret = serial_din(&com_port->dll) & 0xff;
> - ret |= (serial_din(&com_port->dlm) & 0xff) << 8;
> - serial_dout(&com_port->lcr, UART_LCRVAL);
> -
> - return ret;
> -}
> -
> static inline void _debug_uart_putc(int ch)
> {
> struct NS16550 *com_port = (struct NS16550 *)CONFIG_DEBUG_UART_BASE;
>
> - while (!(serial_din(&com_port->lsr) & UART_LSR_THRE)) {
> - if (!NS16550_read_baud_divisor(com_port))
> - return;
> - }
> + while (!(serial_din(&com_port->lsr) & UART_LSR_THRE))
> + ;
> serial_dout(&com_port->thr, ch);
> }
>
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