Re: [PATCH 5/6] tty: serial: Add linflexuart driver for S32V234

[Stefan-gabriel Mirea <stefan-gabriel.mirea@nxp.com>]

On 8/5/2019 6:31 PM, gregkh@linuxfoundation.org wrote:
> On Fri, Aug 02, 2019 at 07:47:23PM +0000, Stefan-gabriel Mirea wrote:
>>
>> +/* Freescale Linflex UART */
>> +#define PORT_LINFLEXUART     121
> 
> Do you really need this modified?

Hello Greg,

This macro is meant to be assigned to port->type in the config_port
method from uart_ops, in order for verify_port to know if the received
serial_struct structure was really targeted for a LINFlex port. It
needs to be defined outside, to avoid "collisions" with other drivers.

As far as I see, uart_set_info() will actually fail at the
"baud_base < 9600" check[1], right after calling verify_port(), when
performing an ioctl() on "/dev/console" with TIOCSSERIAL using a
serial_struct obtained with TIOCGSERIAL. This happens because this
reduced version of the LINFlex UART driver will not touch the uartclk
field of the uart_port (as there is currently no clock support).
Therefore, the linflex_config/verify_port() functions, along with the
PORT_LINFLEXUART macro, may be indeed unnecessary at this point (and
should be added later). Is this what you mean?

Other than that, I do not see anything wrong with the addition of a
define in serial_core.h for this purpose (which is also what most of the
serial drivers do, including amba-pl011.c, mentioned in
Documentation/driver-api/serial/driver.rst as providing the reference
implementation), so please be more specific.

Regards,
Stefan

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/serial_core.c?h=v5.3-rc1#n872