From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>, Rob Herring <robh+dt@kernel.org>,
"Matwey V. Kornilov" <matwey@sai.msu.ru>,
Giulio Benetti <giulio.benetti@micronovasrl.com>,
Heiko Stuebner <heiko@sntech.de>,
Christoph Muellner <christoph.muellner@theobroma-systems.com>,
Jan Kiszka <jan.kiszka@siemens.com>,
devicetree@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH 4/4] serial: 8250: Support rs485 bus termination GPIO
Date: Tue, 5 May 2020 19:10:35 +0300 [thread overview]
Message-ID: <20200505161035.GW185537@smile.fi.intel.com> (raw)
In-Reply-To: <a91b9392e8e7914cae16f59beb1ffe6b335f81c9.1588505407.git.lukas@wunner.de>
On Tue, May 05, 2020 at 04:42:04PM +0200, Lukas Wunner wrote:
> Commit e8759ad17d41 ("serial: uapi: Add support for bus termination")
> introduced the ability to enable rs485 bus termination from user space.
> So far the feature is only used by a single driver, 8250_exar.c, using a
> hardcoded GPIO pin specific to Siemens IOT2040 products.
>
> Provide for a more generic solution by allowing specification of an
> rs485 bus termination GPIO pin in the device tree: Amend the serial
> core to retrieve the GPIO from the device tree (or ACPI table) and amend
> the default ->rs485_config() callback for 8250 drivers to change the
> GPIO on request from user space.
...
> @@ -3331,6 +3332,29 @@ int uart_get_rs485_mode(struct uart_port *port)
> + devm_gpiod_put(dev, port->rs485_term_gpio);
> + port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
Using devm_*() in uart_get_rs485_mode() seems not right.
Why do you need this?
> + GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT);
Parameter has a specific macro GPIOD_OUT_HIGH.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-05-05 16:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 14:42 [PATCH 0/4] rs485 bus termination GPIO Lukas Wunner
2020-05-05 14:42 ` [PATCH 1/4] serial: 8250: Avoid error message on reprobe Lukas Wunner
2020-05-05 16:01 ` Andy Shevchenko
2020-05-06 6:06 ` Lukas Wunner
2020-05-06 10:01 ` Andy Shevchenko
2020-05-06 11:54 ` Lukas Wunner
2020-05-05 14:42 ` [PATCH 2/4] serial: Allow uart_get_rs485_mode() to return errno Lukas Wunner
2020-05-05 14:42 ` [PATCH 3/4] dt-bindings: serial: Add binding for rs485 bus termination GPIO Lukas Wunner
2020-05-05 14:42 ` [PATCH 4/4] serial: 8250: Support " Lukas Wunner
2020-05-05 16:10 ` Andy Shevchenko [this message]
2020-05-06 6:29 ` Lukas Wunner
2020-05-06 10:06 ` Andy Shevchenko
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