From: Linus Walleij <linus.walleij@linaro.org>
To: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: linux-gpio@vger.kernel.org,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Nicolas Ferre <nicolas.ferre@microchip.com>
Subject: Re: [RESEND RFC PATCH 0/2] fixing the gpio ownership
Date: Thu, 18 Jan 2018 11:16:44 +0100 [thread overview]
Message-ID: <CACRpkdbNqn-MJuzq=BpbNYveD-F8Hee2NY6ny4-SJL+F=wHq7g@mail.gmail.com> (raw)
In-Reply-To: <20180115162407.6314-1-ludovic.desroches@microchip.com>
Hi Ludovic, thanks for your patches!
On Mon, Jan 15, 2018 at 5:24 PM, Ludovic Desroches
<ludovic.desroches@microchip.com> wrote:
> A few weeks ago, I have sent an RFC about adding bias support for GPIOs [1].
I was confused I think, because the issue of ownership and adding
bias support were conflated.
I think I discussed properly the ideas I have for pin control properties
vs the GPIOlib API/ABI in my response to patch 1.
> It was motivated by the fact that I wanted to enable the pinmuxing strict mode
> for my pin controller which can muxed a pin as a peripheral or as a GPIO.
So that is a different thing from bias support.
> Enabling the strict mode prevents several devices to be probed because
> requesting a GPIO fails. The pin request function complains about the
> ownership of the GPIO which is different from the mux ownership. I have to
> remove my pinctrl node to avoid this conflict but I need it to configure my
> pins and to set a pull-up bias for my GPIOs.
Okay I think the right solution is to fix the ownership issue, and set
up bias using pin control/config but use the line through gpiolib for now.
> The main issue is that enabling the strict mode will
> break old DTBs.
Yeah we need to work around that.
> I was going to submit patches for this but, after using the
> sysfs which still show me a bad ownership, I decided that it should be fixed.
Yep :)
> So I did these patches. Unfortunately, there are several ways to lead to
> gpiod_request(). It does the trick only for the gpiod_get family. The issue is
> still present with legacy gpio_request and fwnode_get_named_gpiod.
fwnode_get_named_gpiod() must really be fixed too. You probably
want to have things like LEDs and GPIO keys working even if
your pin controller is strict.
I don't care so much about the old functions, I guess you just have
to make sure that the drivers for *your* pin controller all use descriptors
so that you can enable strict mode on *your* pin controller, right?
Restrict your task to this, I'd say.
> It seems
> that more and more drivers are converted to use GPIO descriptors so there is
> some hope.
Yeah I'm doing this when I have time. There is plenty of work...
Help appreciated.
Yours,
Linus Walleij
next prev parent reply other threads:[~2018-01-18 10:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 16:24 [RESEND RFC PATCH 0/2] fixing the gpio ownership Ludovic Desroches
2018-01-15 16:24 ` [RFC PATCH 1/2] pinctrl: add consumer variant for gpio request Ludovic Desroches
2018-01-15 16:24 ` [RFC PATCH 2/2] gpio: provide a consumer when requesting a gpio Ludovic Desroches
2018-01-18 10:30 ` Linus Walleij
2018-01-18 15:22 ` Ludovic Desroches
2018-01-24 13:07 ` Ludovic Desroches
2018-01-24 15:42 ` Andy Shevchenko
2018-01-26 7:32 ` Ludovic Desroches
2018-01-26 17:13 ` Andy Shevchenko
2018-01-29 13:43 ` Ludovic Desroches
2018-01-18 10:16 ` Linus Walleij [this message]
2018-01-18 15:12 ` [RESEND RFC PATCH 0/2] fixing the gpio ownership Ludovic Desroches
2018-01-19 21:02 ` Linus Walleij
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