From: Ludovic Desroches <ludovic.desroches@microchip.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>,
<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 16:12:11 +0100 [thread overview]
Message-ID: <20180118151211.GW2989@rfolt0960.corp.atmel.com> (raw)
In-Reply-To: <CACRpkdbNqn-MJuzq=BpbNYveD-F8Hee2NY6ny4-SJL+F=wHq7g@mail.gmail.com>
On Thu, Jan 18, 2018 at 11:16:44AM +0100, Linus Walleij wrote:
> 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.
>
No problem, at the beginning, I only wanted to enable the strict. Doing
this involves that I have to remove pinctrl nodes for the pins which are
going to be request through the gpiolib to avoid conflicts. These pins
were configured with bias-pull-up. That's why I try to add the bias
support.
> I think I discussed properly the ideas I have for pin control properties
> vs the GPIOlib API/ABI in my response to patch 1.
>
Thanks for the detailed answer about what you have in mind.
> > 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.
>
Well, yes and not! As a consequence of enabling strict mode, I have to
find another way to configure the pins.
> > 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.
>
Yes, I have noticed this issue.
> 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?
>
Right, I have spotted some drivers to fix.
> 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.
>
I will try to handle the ones related to the platforms I am using.
Regards
Ludovic
next prev parent reply other threads:[~2018-01-18 15:12 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 ` [RESEND RFC PATCH 0/2] fixing the gpio ownership Linus Walleij
2018-01-18 15:12 ` Ludovic Desroches [this message]
2018-01-19 21:02 ` Linus Walleij
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