On Thu, Apr 12, 2018 at 02:41:43PM -0700, Andrey Smirnov wrote:
> Using FIFO in LPUART results in subtle serial input draining issues
> which are quite difficult to reproduce and troubleshoot. Since the
> change offered only moderate performance gain revert the code to
> operate in no-FIFO mode to avoid FIFO-related problems alltogether.
>
> Signed-off-by: Andrey Smirnov
Applied, thanks
Sascha
> ---
> drivers/serial/serial_lpuart.c | 4 +---
> include/serial/lpuart.h| 21 +
> 2 files changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
> index 52fb6d39c..8f87f7b9c 100644
> --- a/drivers/serial/serial_lpuart.c
> +++ b/drivers/serial/serial_lpuart.c
> @@ -170,9 +170,7 @@ static int lpuart_serial_probe(struct device_d *dev)
>
> cdev->linux_console_name = "ttyLP";
>
> - lpuart_setup_with_fifo(lpuart->base,
> -clk_get_rate(lpuart->clk),
> -15);
> + lpuart_setup(lpuart->base, clk_get_rate(lpuart->clk));
>
> ret = console_register(cdev);
> if (!ret) {
> diff --git a/include/serial/lpuart.h b/include/serial/lpuart.h
> index 917f644a5..a920291de 100644
> --- a/include/serial/lpuart.h
> +++ b/include/serial/lpuart.h
> @@ -238,22 +238,17 @@ static inline void lpuart_setbrg(void __iomem *base,
> writeb(bfra, base + UARTCR4);
> }
>
> -static inline void lpuart_setup_with_fifo(void __iomem *base,
> - unsigned int refclock,
> - unsigned int twfifo)
> +static inline void lpuart_setup(void __iomem *base,
> + unsigned int refclock)
> {
> /* Disable UART */
> writeb(0, base + UARTCR2);
> writeb(0, base + UARTMODEM);
> writeb(0, base + UARTCR1);
>
> - if (twfifo) {
> - writeb(UARTPFIFO_TXFE | UARTPFIFO_RXFE, base + UARTPFIFO);
> - writeb((u8)twfifo, base + UARTTWFIFO);
> - } else {
> - writeb(0, base + UARTPFIFO);
> - writeb(0, base + UARTTWFIFO);
> - }
> + writeb(0, base + UARTPFIFO);
> + writeb(0, base + UARTTWFIFO);
> +
> writeb(1, base + UARTRWFIFO);
> writeb(UARTCFIFO_RXFLUSH | UARTCFIFO_TXFLUSH, base + UARTCFIFO);
>
> @@ -262,12 +257,6 @@ static inline void lpuart_setup_with_fifo(void __iomem
> *base,
> writeb(UARTCR2_TE | UARTCR2_RE, base + UARTCR2);
> }
>
> -static inline void lpuart_setup(void __iomem *base,
> - unsigned int refclock)
> -{
> - lpuart_setup_with_fifo(base, refclock, 0x00);
> -}
> -
> static inline void lpuart_putc(void __iomem *base, int c)
> {
> if (!(readb(base + UARTCR2) & UARTCR2_TE))
> --
> 2.14.3
>
>
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