linux-kernel - Re: [PATCH v2 2/4] pinctrl: aspeed: Add core pinconf support

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Date:   Mon, 24 Apr 2017 14:54:31 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Andrew Jeffery <andrew@...id.au>
Cc:     Rob Herring <robh+dt@...nel.org>, Joel Stanley <joel@....id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v2 2/4] pinctrl: aspeed: Add core pinconf support

On Fri, Apr 7, 2017 at 2:57 PM, Andrew Jeffery <andrew@...id.au> wrote:

> Several pinconf parameters have a fairly straight-forward mapping onto
> the Aspeed pin controller. These include management of pull-down bias,
> drive-strength, and some debounce configuration.
>
> Pin biasing largely is managed on a per-GPIO-bank basis, aside from the
> ADC and RMII/RGMII pins. As the bias configuration for each pin in a
> bank maps onto a single per-bank bit, configuration tables will be
> introduced to describe the ranges of pins and the supported pinconf
> parameter. The use of tables also helps with the sparse support of
> pinconf properties, and the fact that not all GPIO banks support
> biasing or drive-strength configuration.
>
> Further, as the pin controller uses a consistent approach for bias and
> drive strength configuration at the register level, a second table is
> defined for looking up the the bit-state required to enable or query the
> provided configuration.
>
> Testing for pinctrl-aspeed-g4 was performed on an OpenPOWER Palmetto
> system, and pinctrl-aspeed-g5 on an AST2500EVB as well as under QEMU.
> The test method was to set the appropriate bits via devmem and verify
> the result through the controller's pinconf-pins debugfs file. This
> simultaneously validates the get() path and half of the set() path. The
> remainder of the set() path was validated by configuring a handful of
> pins via the devicetree with the supported pinconf properties and
> verifying the appropriate registers were touched.
>
> Signed-off-by: Andrew Jeffery <andrew@...id.au>

Patch applied.

Yours,
Linus Waleij