[U-Boot] [PATCH v2] serial: nulldev: Add nulldev serial driver

Bin Meng bmeng.cn at gmail.com
Tue Aug 29 01:41:04 UTC 2017

Hi Wilson,

On Fri, Aug 25, 2017 at 11:29 AM, Wilson Lee <wilson.lee at ni.com> wrote:
> From: Keng Soon Cheah <keng.soon.cheah at ni.com>
> Some device the serial console's initialization cannot run early during
> the boot process. Hence, nulldev serial device is helpful on that
> situation.
> For example, if the serial module was implemented in FPGA. Serial
> initialization is prohibited to run until the FPGA was programmed.

I still don't fully understand this. Shouldn't the FPGA serial driver
has some sort of register bits that determine if it's ready? And if
not ready, the FPGA serial driver can do nothing like your null serial
driver does?

> This commit is to adding nulldev serial driver. This will allows the
> default console to be specified as a nulldev.
> Signed-off-by: Joe Hershberger <joe.hershberger at ni.com>
> Signed-off-by: Keng Soon Cheah <keng.soon.cheah at ni.com>
> Cc: Chen Yee Chew <chen.yee.chew at ni.com>
> ---
>  drivers/serial/Kconfig          |  7 ++++++
>  drivers/serial/Makefile         |  1 +
>  drivers/serial/serial_nulldev.c | 48 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 56 insertions(+)
>  create mode 100644 drivers/serial/serial_nulldev.c



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