[U-Boot] [PATCH 2/3] serial: uartlite: Add support for debug console

Thomas Chou
2015-12-15T04:01:07Z

Hi Michal,

On 2015?12?14? 23:50, Michal Simek wrote:
> Hi,
>
> On 14.12.2015 14:14, Thomas Chou wrote:
>> Hi Michal,
>>
>> On 2015?12?11? 19:54, Michal Simek wrote:
>>> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
>>> ---
>>>
>>> drivers/serial/Kconfig | 7 +++++++
>>> drivers/serial/serial_xuartlite.c | 23 +++++++++++++++++++++++
>>> 2 files changed, 30 insertions(+)
>>>
>>> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
>>> index 1fc287ee98ec..f1e221799b81 100644
>>> --- a/drivers/serial/Kconfig
>>> +++ b/drivers/serial/Kconfig
>>> @@ -92,6 +92,13 @@ config DEBUG_UART_S5P
>>> will need to provide parameters to make this work. The driver
>>> will
>>> be available until the real driver-model serial is running.
>>>
>>> +config DEBUG_UART_UARTLITE
>>> + bool "Xilinx Uartlite"
>>> + help
>>> + Select this to enable a debug UART using the serial_uartlite
>>> driver.
>>> + You will need to provide parameters to make this work. The
>>> driver will
>>> + be available until the real driver-model serial is running.
>>> +
>>> config DEBUG_UART_ZYNQ
>>> bool "Xilinx Zynq"
>>> help
>>> diff --git a/drivers/serial/serial_xuartlite.c
>>> b/drivers/serial/serial_xuartlite.c
>>> index 10089f5a34b5..fe87b515d902 100644
>>> --- a/drivers/serial/serial_xuartlite.c
>>> +++ b/drivers/serial/serial_xuartlite.c
>>> @@ -120,3 +120,26 @@ U_BOOT_DRIVER(serial_uartlite) = {
>>> .ops = &uartlite_serial_ops,
>>> .flags = DM_FLAG_PRE_RELOC,
>>> };
>>> +
>>> +#ifdef CONFIG_DEBUG_UART_UARTLITE
>>
>> Better move the "#include <debug_uart.h>" here.
>
> This is the patch I sent some days ago about removing it from this
> location and it was Reviewed twice.
> http://lists.denx.de/pipermail/u-boot/2015-December/236341.html
>
>>

This is because commit 42800ffa7997 ("arm: zynq: Move serial driver to
driver model") added the extra #include <debug_uart.h>. It is this one
should be removed. The original one in commit c54c0a4c1c74 ("arm: zynq:
Support the debug UART") is good. The wrong one was removed.

>>> +void _debug_uart_init(void)
>>
>> Please add "static inline" to void _debug_uart_init(void).
>
> Ok. Will fix this for uartlite and zynq uart in follow up patch.
>
>
>>> +{
>>> + struct uartlite *regs = (struct uartlite *)CONFIG_DEBUG_UART_BASE;
>>> +
>>> + out_be32(&regs->control, 0);
>>> + out_be32(&regs->control, ULITE_CONTROL_RST_RX |
>>> ULITE_CONTROL_RST_TX);
>>> + in_be32(&regs->control);
>>> +}
>>> +
>>> +static inline void _debug_uart_putc(int ch)
>>> +{
>>> + struct uartlite *regs = (struct uartlite *)CONFIG_DEBUG_UART_BASE;
>>> +
>>> + while (in_be32(&regs->status) & SR_TX_FIFO_FULL)
>>> + WATCHDOG_RESET();
>>
>> WATCHDOG_RESET() is not really needed for debug serial output.
>
> TBH I don't think so. There could be watchdog running from early
> bootloader and needs to be service even for debugging purpose.
>

Unless the serial input clock is dead, the serial shift out in UART
won't take so long to trigger watchdog.

Best regards,
Thomas