From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Peter Rosin <peda@axentia.se>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [REGRESSION] gpio hogging fails with pinctrl gpio drivers
Date: Thu, 20 Feb 2020 18:19:12 +0000 [thread overview]
Message-ID: <20200220181911.GD25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAHQ1cqFeMKrb-MxnifVJXfGciQH8wsjS1dSSeTTc0R06jLT+Cw@mail.gmail.com>
On Thu, Feb 20, 2020 at 09:28:14AM -0800, Andrey Smirnov wrote:
> On Thu, Feb 20, 2020 at 12:18 AM Linus Walleij <linus.walleij@linaro.org> wrote:
> >
> > On Thu, Feb 6, 2020 at 6:33 PM Russell King - ARM Linux admin
> > <linux@armlinux.org.uk> wrote:
> >
> > > It seems that sometime between 4.20 and 5.5, something has broken the
> > > ability to specify gpio-hogs in DT for GPIOs that are written around
> > > pinctrl drivers.
> > (explanation that makes perfect sense)
> > > Consequently, adding a gpio-hog to DT for this driver results in the
> > > driver endlessly returning -EPROBE_DEFER.
> >
> > I suspect this is sx150x-specific and suspect these two commits:
> >
> > 1a1d39e1b8dd pinctrl: sx150x: Register pinctrl before adding the gpiochip
> > b930151e5b55 pinctrl: sx150x: Add a static gpio/pinctrl pin range mapping
> >
> > I suppose people weren't using hogs very much with the sx150x and
> > it didn't turn up in testing so far.
> >
> > I don't think for example pinctrl-stmfx.c has this problem, as it registers
> > the pin ranges from the device tree as part of the core code.
> > But other drivers calling gpiochip_add_pin_range() may be experiencing
> > this.
> >
> > Peter/Andrey, do you have some idea? Have you tested this usecase (hogs)
> > with the sx150x?
> >
>
> Haven't done any GPIO hogging on sx150x, unfortunately. My use-cases were:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/vf610-zii-dev-rev-c.dts
>
> and
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/vf610-zii-scu4-aib.dts
>
> which didn't have any hogs so far (there's a chance Russell is using
> the former for his experiments, so maybe that'll change). I don't any
> useful input on this regression, sorry. I do have Rev C. board readily
> available, so I can provide Tested-by's if I am CC'd on fixes.
The ZII dev rev C is where I had the hog as a means of kicking the
88x3310 PHY out of reset.
I've now converted it to a proper MDIO bus-level reset, so I no
longer have the hog, and I no longer care about the regression - but
that's not to say it shouldn't be fixed, as the code is wrong.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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prev parent reply other threads:[~2020-02-20 18:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200206173247.GX25745@shell.armlinux.org.uk>
2020-02-20 8:17 ` [REGRESSION] gpio hogging fails with pinctrl gpio drivers Linus Walleij
2020-02-20 10:12 ` Peter Rosin
2020-02-20 17:28 ` Andrey Smirnov
2020-02-20 18:19 ` Russell King - ARM Linux admin [this message]
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