[PATCH v6 01/12] pinctrl: Add pinmux property support to pinctrl-generic

[Tom Rini]

On Mon, Sep 14, 2020 at 11:01:55AM -0400, Sean Anderson wrote:

> The pinmux property allows for smaller and more compact device trees,
> especially when there are many pins which need to be assigned individually.
> Instead of specifying an array of strings to be parsed as pins and a
> function property, the pinmux property contains an array of integers
> representing pinmux groups. A pinmux group consists of the pin identifier
> and mux settings represented as a single integer or an array of integers.
> Each individual pin controller driver specifies the exact format of a
> pinmux group. As specified in the Linux documentation, a pinmux group may
> be multiple integers long. However, no existing drivers use multi-integer
> pinmux groups, so I have chosen to omit this feature. This makes the
> implementation easier, since there is no need to allocate a buffer to do
> endian conversions.
> 
> Support for the pinmux property is done differently than in Linux.  As far
> as I can tell, inversion of control is used when implementing support for
> the pins and groups properties to avoid allocating. This results in some
> duplication of effort; every property in a config node is parsed once for
> each pin in that node. This is not such an overhead with pins and groups
> properties, since having multiple pins in one config node does not occur
> especially often. However, the semantics of the pinmux property make such a
> configuration much more appealing. A future patch could parse all config
> properties at once and store them in an array. This would make it easier to
> create drivers which do not function solely as callbacks from
> pinctrl-generic.
> 
> This commit increases the size of the sandbox build by approximately 48
> bytes.  However, it also decreases the size of the K210 device tree by 2
> KiB from the previous version of this series.
> 
> The documentation has been updated from the last Linux commit before it was
> split off into yaml files.
> 
> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>

Applied to u-boot/master, thanks!

-- 
Tom
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