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SubjectRe: Bug introduced in the of_get_named_gpiod_flags function.
Hi Wojciech,

(Thanks also Randy for forwarding this!)

On Wed, Oct 10, 2018 at 6:32 PM wzab <> wrote:

> The function of_get_named_gpiod_flags in older versions of the kernel
> (up to 4.7.10 - )
> 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: )
> the random, unitialized value from the stack in of_find_gpio
> ( )
> 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:

It seems the commit removing this is:

commit 762c2e46c0591d207289105c8718e4adf29b2b34
"gpio: of: remove of_gpiochip_and_xlate() and struct gg_data"

But I honestly don't see a problem with it.

You are referencing an out-of-tree driver. Use the in-tree gpio-xilinx.c
that does not do any custom xlate and you will be fine.

I looked over the driver doing custom flag translation in the kernel tree,
and they all set flags, so this is not a problem in the upstream kernel.

Linus Walleij

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