From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Drew Fustini <drew@beagleboard.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] gpiolib: Allow name duplicates of "" and "NC"
Date: Wed, 16 Dec 2020 14:38:08 -0600 [thread overview]
Message-ID: <X9pwML9OLalPI0O4@builder.lan> (raw)
In-Reply-To: <20201216195357.GA2583366@x1>
On Wed 16 Dec 13:53 CST 2020, Drew Fustini wrote:
> On Tue, Dec 15, 2020 at 09:03:08AM -0800, Bjorn Andersson wrote:
> > Not all GPIO pins are exposed to the world and this is typically
> > described by not giving these lines particular names, commonly "" or
> > "NC".
> >
> > With the recent introduction of '2cd64ae98f35 ("gpiolib: Disallow
> > identical line names in the same chip")' any gpiochip with multiple such
> > pins will refuse to probe.
> >
> > Fix this by treating "" and "NC" as "no name specified" in
> > gpio_name_to_desc()
> >
> > Fixes: 2cd64ae98f35 ("gpiolib: Disallow identical line names in the same chip")
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
> >
> > The introduction of 2cd64ae98f35 breaks pretty much all Qualcomm boards and
> > grepping the DT tree indicates that other vendors will have the same problem.
> >
> > In addition to this the am335x-* boards will also needs "[NC]", "[ethernet]",
> > "[emmc"], "[i2c0]", "[SYSBOOT]" and "[JTAG]" added to this list to allow
> > booting v5.11 with the past and present dtb/dts files.
>
> I am the one who added the gpio line names to the am335x dts board
> files, and I am happy to change them if it will make unique line name
> logic simpler.
>
> I used the notation of "[<non-gpio-functionality>]" to make it easy for
> the user to realize that the corresponding gpiolines could not be used
> on these boards (BeagleBone and PocketBeagle) for actual GPIO. I used
> generic names like "[ethernet]" because I didn't think it made sense
> to confuse the user by using the precise name of the non-gpio function
> (such as "[gmii1_rxd0]"). I could post a patch for the dts files that
> restores unique names for "[ethernet]", "[emmc"], "[i2c0]",
> "[SYSBOOT]" and "[JTAG]".
>
> As for "[NC]", the BGA balls corresponding to these gpio lines are
> simply not connected to any circuits on the board. I happy to change
> that to whatever name people prefer for a non-connected pin ("", "NC",
> etc).
>
I think this is the right thing to do, but we can't have gpiolib refuse
to probe existing DTBs - at least not until some grace period has
expired.
Regards,
Bjorn
prev parent reply other threads:[~2020-12-16 20:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 17:03 [PATCH] gpiolib: Allow name duplicates of "" and "NC" Bjorn Andersson
2020-12-15 17:42 ` Bartosz Golaszewski
2020-12-15 17:59 ` Bjorn Andersson
2020-12-16 12:46 ` Linus Walleij
2020-12-16 18:40 ` Bjorn Andersson
2020-12-16 20:50 ` Linus Walleij
2020-12-16 19:53 ` Drew Fustini
2020-12-16 20:38 ` Bjorn Andersson [this message]
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