Messages in this thread | | | From | "Matwey V. Kornilov" <> | Date | Wed, 6 Jun 2018 21:55:22 +0300 | Subject | Re: [PATCH 1/4] serial: 8250: Copy em485 from port to real port. |
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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). I suppose it is only important for use-case when rs485 used as slave (peripheral role).
> > -- > Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Intel Finland Oy
-- With best regards, Matwey V. Kornilov
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