[RFC PATCH] imx: skip unused compatible strings in drivers

[Anatolij Gustschin <agust@denx.de>]

On Tue, 26 May 2020 13:25:00 +0200
Marek Vasut marex at denx.de wrote:

> On 5/26/20 1:12 PM, Soeren Moch wrote:
> > On 25.05.20 22:24, Anatolij Gustschin wrote:  
> >> Converting to DM increases binary size and breaks building some
> >> boards (i.e. tbs2910, gcc 9.2). The approach to address this issue
> >> via cutting off unused properties/nodes in device tree via custom
> >> u-boot.dtsi was not welcome, even if the affected boards do not
> >> pass the built-in device tree to the kernel.  
> > But there is CONFIG_OF_REMOVE_PROPS="dmas dma-names interrupt-parent
> > interrupts interrupts-extended interrupt-names interrupt-map
> > interrupt-map-mask" in tbs2910_defconfig. So removing properties is
> > already done via this config option. Removing nodes is not implemented
> > (yet? AFAIK). But would be welcome if someone implements this in a
> > similar way, I think.  
> 
> Why don't we turn this the other way around -- put the { compat string ,
> driver } tuple list into a U-Boot linker list, then filter this linker
> list against a DT which will be used for the platform (what if there are
> multiple DTs?), and then scrub all unreferrenced symbols.

This might be a topic again when new bloat causes build breakage
again. For now I've succeeded to build the tbs2910 board with
default CI tool chain without this patch (by making DM_VIDEO parts
optional). Stripping unused compatible entries doesn't save much here
(around 800 bytes). So the question is if it is worth the effort
to implement such scrubbing.

--
Anatolij