* Shawn Guo <shawn....@linaro.org> [120129 18:30]: > On Fri, Jan 27, 2012 at 07:43:36AM -0800, Simon Glass wrote: > ... > > The cost of the pmx@dta node is about 12 bytes for the header (it > > depends on the length of the name), and each of the properties above > > is 16 bytes. So in total this node is 76 bytes. If we have 250 pins > > being muxed as Tegra3 then this is about 20KB (including a bit of > > slack for longer names). My point about being able to 'optimise out' > > some of these remains, though, but probably not for the kernel. > > > > Stephen's 'mux' property uses 12 bytes plus 8 bytes per pin/group (I > > am removing the prefixes): > > > > mux = > > <PG_DTA MUX_SDIO1> > > <PG_DTD MUX_SDIO1>; > > > > so 28 bytes. What I proposed would use (12 + 2 * 16) per pin/group, or > > 44 bytes (60% bigger): > > > It's not only about size but also run-time tree travelling efficiency. > Your proposal requires every single pin show as a node in device tree. > Looking at these for_each_node_by_*() APIs in include/linux/of.h, you > might agree we should avoid bloating device tree with so many nodes.
And that's why I'm suggesting two bindings: A minimal pinctrl-static binding and more verbose pinctrl-dynamic binding. AFAIK the number of pinctrl-dynamic bindings needed are just a fraction of the pinctrl-static bindings. So the extra parsing needed for a few pinctrl-dynamic bindings should not matter. Sure it would be nice to have it all in a single binding, but these bindings have conflicting requirements. So it may not be possible to do it in a single binding in an efficient way. Regards, Tony _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss