am curious, are there any non-printable character that can be used to kick it?
On Fri, Apr 9, 2021 at 4:35 PM Kinsey Moore <kinsey.mo...@oarcorp.com> wrote:
>
> Constantly reinitializing the Cadence UART on every character output
> causes data corruption/loss on some ZynqMP hardware. Only initialize
> the UART once for early output and give it a kick on startup.
> ---
> bsps/aarch64/xilinx-zynqmp/console/console.c | 6 ++++++
> bsps/shared/dev/serial/zynq-uart-polled.c | 9 ++++++---
> 2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/bsps/aarch64/xilinx-zynqmp/console/console.c
> b/bsps/aarch64/xilinx-zynqmp/console/console.c
> index 84e158d3f6..8b12d59d4c 100644
> --- a/bsps/aarch64/xilinx-zynqmp/console/console.c
> +++ b/bsps/aarch64/xilinx-zynqmp/console/console.c
> @@ -112,6 +112,12 @@ static void zynqmp_debug_console_early_init(char c)
> &zynqmp_uart_instances[BSP_CONSOLE_MINOR].base;
>
> zynq_uart_initialize(base);
> + BSP_output_char = zynqmp_debug_console_out;
> + /*
> + * Some ZynqMP UARTs have a hardware bug that causes TX/RX logic restarts
> to
> + * require a kick after baud rate registers are initialized.
> + */
> + zynqmp_debug_console_out(' ');
> zynqmp_debug_console_out(c);
> }
>
> diff --git a/bsps/shared/dev/serial/zynq-uart-polled.c
> b/bsps/shared/dev/serial/zynq-uart-polled.c
> index 442431d502..74e7255ec2 100644
> --- a/bsps/shared/dev/serial/zynq-uart-polled.c
> +++ b/bsps/shared/dev/serial/zynq-uart-polled.c
> @@ -128,14 +128,17 @@ void zynq_uart_initialize(rtems_termios_device_context
> *base)
>
> regs->control &= ~(ZYNQ_UART_CONTROL_RXEN | ZYNQ_UART_CONTROL_TXEN);
> regs->control = ZYNQ_UART_CONTROL_RXDIS
> - | ZYNQ_UART_CONTROL_TXDIS
> - | ZYNQ_UART_CONTROL_RXRES
> - | ZYNQ_UART_CONTROL_TXRES;
> + | ZYNQ_UART_CONTROL_TXDIS;
> regs->mode = ZYNQ_UART_MODE_CHMODE(ZYNQ_UART_MODE_CHMODE_NORMAL)
> | ZYNQ_UART_MODE_PAR(ZYNQ_UART_MODE_PAR_NONE)
> | ZYNQ_UART_MODE_CHRL(ZYNQ_UART_MODE_CHRL_8);
> regs->baud_rate_gen = ZYNQ_UART_BAUD_RATE_GEN_CD(brgr);
> regs->baud_rate_div = ZYNQ_UART_BAUD_RATE_DIV_BDIV(bauddiv);
> + /* A Tx/Rx logic reset must be issued after baud rate manipulation */
> + regs->control = ZYNQ_UART_CONTROL_RXDIS
> + | ZYNQ_UART_CONTROL_TXDIS
> + | ZYNQ_UART_CONTROL_RXRES
> + | ZYNQ_UART_CONTROL_TXRES;
> regs->rx_fifo_trg_lvl = ZYNQ_UART_RX_FIFO_TRG_LVL_RTRIG(0);
> regs->rx_timeout = ZYNQ_UART_RX_TIMEOUT_RTO(0);
> regs->control = ZYNQ_UART_CONTROL_RXEN
> --
> 2.20.1
>
> _______________________________________________
> devel mailing list
> devel@rtems.org
> http://lists.rtems.org/mailman/listinfo/devel
_______________________________________________
devel mailing list
devel@rtems.org
http://lists.rtems.org/mailman/listinfo/devel
