From: Lukas Wunner <lukas@wunner.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
"Jiri Slaby" <jirislaby@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Johan Hovold" <johan@kernel.org>,
"Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
"Raymond Tan" <raymond.tan@intel.com>,
"Heiko Stuebner" <heiko@sntech.de>
Subject: Re: [PATCH 1/7] serial: 8250_dwlib: RS485 HW half duplex support
Date: Tue, 8 Mar 2022 21:30:14 +0100 [thread overview]
Message-ID: <20220308203014.GA11096@wunner.de> (raw)
In-Reply-To: <CAHp75Vfd-bi3s=JnNTyov4C7prNhwuWHWsUC6n9pM_E+d4picg@mail.gmail.com>
On Tue, Mar 08, 2022 at 04:53:56PM +0200, Andy Shevchenko wrote:
> On Tue, Mar 8, 2022 at 4:50 PM Lukas Wunner <lukas@wunner.de> wrote:
> > Of course, if hardware-assisted DE assertion requires a particular pinmux
> > state, we could double-check whether that pinmux state is set.
>
> I'm wondering how to achieve this.
On DT platforms, the devicetree specifies the pin controller settings
which need to be configured for a device to be usable, e.g.:
pinctrl-names = "default";
pinctrl-0 = <...>;
Before a driver is bound to the device, really_probe() in drivers/base/dd.c
calls pinctrl_bind_pins() which configures the pin controller accordingly.
In other words, the OS is fully in charge of configuring the pinmux.
I'm not sure how this is done on ACPI platforms. If the pinmux is
exclusively under the control of the platform firmware and the OS has
no way of getting or setting the pinmux configuration, then that would
be a competitive disadvantage vis-à-vis DT platforms which should really
be addressed. However I notice there are various drivers for Intel
chipsets in drivers/pinctrl/intel/, so surely there's a way to let the
OS handle pinmux settings?
Thanks,
Lukas
next prev parent reply other threads:[~2022-03-08 20:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-02 9:55 [PATCH 0/7] Add RS485 support to DW UART Ilpo Järvinen
2022-03-02 9:56 ` [PATCH 1/7] serial: 8250_dwlib: RS485 HW half duplex support Ilpo Järvinen
2022-03-06 18:48 ` Lukas Wunner
2022-03-06 22:07 ` Andy Shevchenko
2022-03-07 9:19 ` Ilpo Järvinen
2022-03-07 19:18 ` Lukas Wunner
2022-03-07 19:39 ` Andy Shevchenko
2022-03-08 12:16 ` Ilpo Järvinen
2022-03-08 12:22 ` Lukas Wunner
2022-03-08 12:59 ` Ilpo Järvinen
2022-03-08 14:50 ` Lukas Wunner
2022-03-08 14:53 ` Andy Shevchenko
2022-03-08 20:30 ` Lukas Wunner [this message]
2022-03-09 9:51 ` Ilpo Järvinen
2022-03-07 10:54 ` Ilpo Järvinen
2022-03-09 8:52 ` Lukas Wunner
2022-03-09 12:19 ` Ilpo Järvinen
2022-03-09 12:59 ` Lukas Wunner
2022-03-02 9:56 ` [PATCH 2/7] serial: 8250_dwlib: RS485 HW full " Ilpo Järvinen
2022-03-06 18:51 ` Lukas Wunner
2022-03-07 9:22 ` Ilpo Järvinen
2022-03-02 9:56 ` [RFC PATCH 3/7] serial: 8250_dwlib: Implement SW half " Ilpo Järvinen
2022-03-06 19:21 ` Lukas Wunner
2022-03-06 22:13 ` Andy Shevchenko
2022-03-02 9:56 ` [PATCH 4/7] dt_bindings: snps-dw-apb-uart: Add RS485 Ilpo Järvinen
2022-03-02 17:47 ` Rob Herring
2022-03-02 9:56 ` [RFC PATCH 5/7] serial: termbits: ADDRB to indicate 9th bit addressing mode Ilpo Järvinen
2022-03-02 9:56 ` [RFC PATCH 6/7] serial: General support for multipoint addresses Ilpo Järvinen
2022-03-06 19:40 ` Lukas Wunner
2022-03-07 9:48 ` Ilpo Järvinen
2022-03-09 19:05 ` Lukas Wunner
2022-03-10 12:29 ` Ilpo Järvinen
2022-03-10 14:09 ` Andy Shevchenko
2022-03-02 9:56 ` [RFC PATCH 7/7] serial: 8250_dwlib: Support for 9th bit multipoint addressing Ilpo Järvinen
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