[PATCH RFC 0/3] clk: support arbitrary clk_register() sequence

[Tom Rini]

On Sat, Jun 21, 2025 at 06:54:17PM +0800, Yang Xiwen wrote:

> Currently U-Boot clk framework mandates the sequence of registering clks
> to begin from root, and then its children. This is an addtional
> requirement that doesn't exist in Linux kernel, which makes clk driver
> porting more difficult.
> 
> Let's handle this entirely in clk framework and give driver the freedom
> to register clocks in any order.
> 
> This is done by assigning the parent "lazily". It will cache the parent
> name in the core clk struct and try to refresh it when clk consumers
> call clk_get_parent(). It's transparent to clk consumers as long as they
> only use APIs provided by clk framework.
> 
> I've ran `ut dm clk*` and verified these commits does not break any
> existing testcases. Though no new testcase is added because I think
> existing testcases already test the logic very well.

Sorry for the very late review. When I build this on say
rock-4c-plus-rk3399 this is the size growth I see:
            rock-4c-plus-rk3399: all +228 spl/u-boot-spl:all +500 spl/u-boot-spl:text +500 text +228 tpl/u-boot-tpl:all +552 tpl/u-boot-tpl:text +552
               u-boot: add: 1/0, grow: 1/0 bytes: 228/0 (228)
                 function                                   old     new   delta
                 device_reparent                              -     120    +120
                 clk_get_parent                              56     164    +108
               spl-u-boot-spl: add: 4/0, grow: 1/0 bytes: 500/0 (500)
                 function                                   old     new   delta
                 uclass_find_device_by_namelen                -     172    +172
                 device_reparent                              -     120    +120
                 clk_get_parent                              56     144     +88
                 uclass_find_device_by_name                   -      68     +68
                 uclass_get_device_by_name                    -      52     +52
               tpl-u-boot-tpl: add: 5/0, grow: 1/0 bytes: 552/0 (552)
                 function                                   old     new   delta
                 uclass_find_device_by_namelen                -     172    +172
                 device_reparent                              -     120    +120
                 clk_get_parent                              56     144     +88
                 uclass_find_device_by_name                   -      68     +68
                 uclass_get_device_by_name                    -      52     +52
                 strncmp                                      -      52     +52

(using buildman's 'bloat' features to report size change). I'm fine with
the growth in U-Boot itself, but that's just too much in SPL and TPL and
we need to figure out if we can avoid that somehow.

-- 
Tom
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