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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Mon, 24 Sep 2018 10:13:02 +0200
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Subject: Re: [PATCH 2/2] gpiolib: Fix array members of same chip processed separately
To:     Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
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On Mon, Sep 24, 2018 at 1:52 AM Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:

> New code introduced by commit bf9346f5d47b ("gpiolib: Identify arrays
> matching GPIO hardware") forcibly tries to find an array member which
> has its array index number equal to its hardware pin number and set
> up an array info for possible fast bitmap processing of all arrray
> pins belonging to that chip which also satisfy that numbering rule.
>
> Depending on array content, it may happen that consecutive array
> members which belong to the same chip but don't have array indexes
> equal to their pin hardware numbers will be split into groups, some of
> them processed together via the fast bitmap path, and rest of them
> separetely.  However, applications may expect all those pins being
> processed together with a single call to .set_multiple() chip callback,
> like that was done before the change.
>
> Limit applicability of fast bitmap processing path to cases where all
> pins of consecutive array members starting from 0 which belong to the
> same chip have their hardware numbers equal to their corresponding
> array indexes.  That should still speed up processing of applications
> using whole GPIO banks as I/O ports, while not breaking simultaneous
> manipulation of consecutive pins of the same chip which don't follow
> the equal numbering rule.
>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>

Patch applied!

Yours,
Linus Walleij