linux-kernel - Re: [PATCH 0/7] serial: 8250: Add rs485 emulation to 8250

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Message-ID: <20200318144320.GL1922688@smile.fi.intel.com>
Date:   Wed, 18 Mar 2020 16:43:20 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Heiko Stuebner <heiko@...ech.de>, Lukas Wunner <lukas@...ner.de>
Cc:     gregkh@...uxfoundation.org, jslaby@...e.com,
        matwey.kornilov@...il.com, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] serial: 8250: Add rs485 emulation to 8250_dw

+Cc: Lukas, who did recently some work WRT RS485 support in 8250.

On Wed, Mar 18, 2020 at 03:26:33PM +0100, Heiko Stuebner wrote:
> This series tries to revive the work of Giulio Benetti from 2018 [0]
> which seemed to have stalled at that time.
> 
> The board I needed that on also had the additional caveat that it
> uses non-standard pins for DE/RE so needed gpio mctrl layer as well
> and even more special needed to control the RE pin manually not as
> part of it being connected to the DE signal as seems to be the standard.
> 
> So I've marked the patch doing this as DTR pin as RFC but that patch
> isn't needed for the other core functionality, so could also be left out.

Thank you, I'll look at them later on.

> Changes from the 2018 submission include:
> - add timeout when waiting for fifos to clear using a new helper
> - move on-boot enablement of the rs485 mode to after registering
>   the port. This saves having to copy the em485 struct as done
>   originally, which also ran into spinlock-debug warnings when testing
>   and also makes it actually possible to use the mctrl gpio layer
>   for non-standard gpios.
> 
> [0] Link: https://lore.kernel.org/linux-serial/20180601124021.102970-1-giulio.benetti@micronovasrl.com/
> 
> Giulio Benetti (4):
>   serial: 8250: Make em485_rts_after_send() set mctrl according to rts
>     state.
>   serial: 8250: Handle case port doesn't have TEMT interrupt using
>     em485.
>   serial: 8250_dw: add em485 support
>   serial: 8250_dw: allow enable rs485 at boot time
> 
> Heiko Stuebner (3):
>   serial: 8250: add serial_in_poll_timeout helper
>   serial: 8250: Start rs485 after registering port if rs485 is enabled
>     in probe
>   serial: 8250: handle DTR in rs485 emulation
> 
>  drivers/tty/serial/8250/8250.h      | 36 ++++++++++++++++++++-
>  drivers/tty/serial/8250/8250_core.c |  9 ++++++
>  drivers/tty/serial/8250/8250_dw.c   | 35 +++++++++++++++++++-
>  drivers/tty/serial/8250/8250_of.c   |  2 +-
>  drivers/tty/serial/8250/8250_omap.c |  2 +-
>  drivers/tty/serial/8250/8250_port.c | 50 +++++++++++++++++++++++------
>  include/linux/serial_8250.h         |  1 +
>  7 files changed, 121 insertions(+), 14 deletions(-)
> 
> -- 
> 2.24.1
> 

-- 
With Best Regards,
Andy Shevchenko