Messages in this thread | | | Subject | Re: [PATCH 1/4] serial: 8250: Copy em485 from port to real port. | From | Giulio Benetti <> | Date | Wed, 6 Jun 2018 21:15:15 +0200 |
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Il 06/06/2018 20:55, Matwey V. Kornilov ha scritto: > 2018-06-06 16:11 GMT+03:00 Andy Shevchenko <andriy.shevchenko@linux.intel.com>: >> On Wed, 2018-06-06 at 14:15 +0200, Giulio Benetti wrote: >>> Il 06/06/2018 13:56, Andy Shevchenko ha scritto: >>>> On Wed, 2018-06-06 at 11:49 +0200, Giulio Benetti wrote: >>>>> em485 gets lost during >>>>> >>>>> Copy em485 to final uart port. >>>>> >>>> >>>> Is it needed at all? >>>> >>>> The individual driver decides either to use software emulation (and >>>> calls explicitly serial8250_em485_init() for that) or do HW assisted >>>> stuff. >>> >>> In 8250_dw.c, during probe(), I need to call dw8250_rs485_config() >>> against local struct uart_8250_port uart = {}; >>> Inside serial8250_register_8250_port() not all uart fields are >>> copied(em485 too). >>> So after probe, em485 is NULL. >>> >>> Another way could be to call dw8250_rs485_config() against real uart >>> port, after calling serial8250_register_8250_port(), >>> would it make sense? >> >> Look at OMAP case closely. They have a callback to configure RS485 which >> is called in uart_set_rs485_config() which is called whenever user >> space does TIOCGRS485 IOCTL. >> >> So, it's completely driven by user space which makes sense by my >> opinion. > > AFAIU, Giulio wants to add support for rs485-enabled-at-boot-time > device tree option (see bindings/serial/rs485.txt for reference).
Yes, I want to add support for "rs485-enabled-at-boot-time" property, maybe I had to write better commit log and a cover letter. Sorry.
> I suppose it is only important for use-case when rs485 used as slave > (peripheral role).
It's important also for master, because RTS, if RTS_AFTER_SEND is set, remains not asserted(trasnmission) until userspace opens that serial port.
Sorry again for not explaining myself well.
-- Giulio Benetti CTO
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