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Date: Wed, 16 Dec 2020 11:53:57 -0800 From: Drew Fustini <drew@...gleboard.org> To: Bjorn Andersson <bjorn.andersson@...aro.org> Cc: Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <bgolaszewski@...libre.com>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org Subject: Re: [PATCH] gpiolib: Allow name duplicates of "" and "NC" 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@...aro.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). Thanks, Drew
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