Hi David,
On Sat, Feb 03, 2018 at 10:14:31AM +0100, Maxime Ripard wrote:
> From: Heiko Stuebner <heiko.stuebner@xxxxxx>
>
> On i.MX, which carries a lot of pin-groups of which most are unused on
> individual boards, they noticed that this plethora of nodes also results
> in the runtime-lookup-performance also degrading [0].
>
> A i.MX-specific solution defining the pingroups in the board files but
> using macros to reference the pingroup-data was not well received.
>
> This patch is trying to solve this issue in a more general way, by
> adding the ability to mark nodes as needing to be referenced somewhere
> in the tree.
>
> To mark a node a needing to be referenced it must be prefixed with
> /delete-if-unreferenced/. This makes dtc check the nodes reference-status
> when creating the flattened tree, dropping it if unreferenced.
>
> For example, the i.MX6SL pingroup
>
> /delete-if-unreferenced/ pinctrl_ecspi1_1: ecspi1grp-1 {
> fsl,pins = <
> MX6SL_PAD_ECSPI1_MISO__ECSPI1_MISO 0x100b1
> MX6SL_PAD_ECSPI1_MOSI__ECSPI1_MOSI 0x100b1
> MX6SL_PAD_ECSPI1_SCLK__ECSPI1_SCLK 0x100b1
> >;
> };
>
> would only be included in the dtb if it got referenced somewhere
> as pingroup via
>
> node {
> pinctrl-0 <&pinctrl_ecscpi1_1>;
> };
>
> [0] http://thread.gmane.org/gmane.linux.ports.arm.kernel/275912/
Have you been able to take a look at this?
Thanks!
Maxime
--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
Attachment:
signature.asc
Description: PGP signature
