linux-kernel - Re: [PATCH 14/16] gpio: Add support for banked GPIO controllers

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Message-ID: <20170914233731.GU5024@atomide.com>
Date:   Thu, 14 Sep 2017 16:37:32 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Grygorii Strashko <grygorii.strashko@...com>,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH 14/16] gpio: Add support for banked GPIO controllers

* Linus Walleij <linus.walleij@...aro.org> [170914 07:00]:
> On Fri, Sep 1, 2017 at 8:57 PM, Thierry Reding <thierry.reding@...il.com> wrote:
> 
> > From: Thierry Reding <treding@...dia.com>
> >
> > Some GPIO controllers are subdivided into multiple logical blocks called
> > banks (or ports). This is often caused by the design assigning separate
> > resources, such as register regions or interrupts, to each bank, or some
> > set of banks.
> >
> > This commit adds support for describing controllers that have such a
> > banked design and provides common code for dealing with them.
> >
> > Signed-off-by: Thierry Reding <treding@...dia.com>
> 
> This patch makes me really happy.
> 
> It pulls in a lot of weirdness to the OF core and creates a coherent
> way of handling these "banked" GPIO chips.
> 
> CC to Tony to make sure he checks that OMAP is ready to use this
> too.

Adding Grygorii to Cc as well, we'll take a look.

Probably the runtime PM will be an issue here still. We must currently
do runtime PM on per GPIO bank basis instead of per GPIO pin level as
we constantly runtime_suspend/resume the whole GPIO bank for idle modes
on the SoCs that support PM. So the usage count for the bank needs to
be either 0 or 1 and cannot be the lines used in the bank.

Regards,

Tony