From: Randy Dunlap <rdunlap@infradead.org>
To: wzab@ise.pw.edu.pl, LKML <linux-kernel@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
Subject: Re: Bug introduced in the of_get_named_gpiod_flags function.
Date: Wed, 10 Oct 2018 09:39:29 -0700 [thread overview]
Message-ID: <4695559c-3f80-584a-c943-37a3bd9c24a7@infradead.org> (raw)
In-Reply-To: <90dbf770-5262-5128-e585-c44d086568f9@ise.pw.edu.pl>
[adding linux-gpio + Linus W.]
On 10/10/18 9:13 AM, wzab wrote:
> Hi,
>
> The function of_get_named_gpiod_flags in older versions of the kernel
> (up to 4.7.10 - https://elixir.bootlin.com/linux/v4.7.10/source/drivers/gpio/gpiolib-of.c#L75 )
> contained an important workaround:
>
> /* .of_xlate might decide to not fill in the flags, so clear it. */if (flags)
> *flags = 0; Unfortunately, newer kernels do not contain it. Therefore if the
> "xlat" function in the gpiochip driver does not set flags, (like e.g.
> the Xilinx AXI GPIO driver: https://github.com/Xilinx/linux-xlnx/blob/c2ba891326bb472da59b6a2da29aca218d337687/drivers/gpio/gpio-xilinx.c#L262 )
> the random, unitialized value from the stack in of_find_gpio
> ( https://elixir.bootlin.com/linux/v4.18.13/source/drivers/gpio/gpiolib-of.c#L228 )
> is used, which results in random settings of e.g., OPEN DRAIN or OPEN SOURCE mode.
>
> I have also reported the problem in the Xilinx forum: https://forums.xilinx.com/t5/Embedded-Linux/Bug-in-of-get-named-gpiod-flags-function-in-the-kernel-random/td-p/897695
>
> With best regards,
> Wojciech Zabolotny
>
>
>
--
~Randy
next prev parent reply other threads:[~2018-10-10 16:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 16:13 Bug introduced in the of_get_named_gpiod_flags function wzab
2018-10-10 16:39 ` Randy Dunlap [this message]
2018-10-11 8:27 ` Linus Walleij
2018-10-12 8:54 ` Michal Simek
2018-10-13 15:53 ` wzabolot
2018-10-13 16:23 ` Linus Walleij
2018-10-15 13:41 ` Wojciech Zabołotny
2018-10-10 16:30 Wojciech Zabołotny
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