Hi Linus, On Tue, Nov 08, 2022 at 02:25:04PM +0100, Linus Walleij wrote: > On Fri, Nov 4, 2022 at 2:32 PM Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > > The UX500 PRCMU "clkout" clock implements a mux with a set_parent hook, > > but doesn't provide a determine_rate implementation. > > > > This is a bit odd, since set_parent() is there to, as its name implies, > > change the parent of a clock. However, the most likely candidate to > > trigger that parent change is a call to clk_set_rate(), with > > determine_rate() figuring out which parent is the best suited for a > > given rate. > > > > The other trigger would be a call to clk_set_parent(), but it's far less > > used, and it doesn't look like there's any obvious user for that clock. > > > > So, the set_parent hook is effectively unused, possibly because of an > > oversight. However, it could also be an explicit decision by the > > original author to avoid any reparenting but through an explicit call to > > clk_set_parent(). > > It is actually set up from the device tree, typically like this: > > /* clkout1 from ACLK divided by 8 */ > clocks = <&clkout_clk DB8500_CLKOUT_1 DB8500_CLKOUT_SRC_ACLK 8>; > > So the parent (source) and divisor comes in there. > > clk->source and clk->divider is already set up when clk_hw_register() is > called. I wasn't aware that we had such bindings. AFAIUI, it looks redundant with assigned-clock-rates and assigned-clock-parents, could we deprecate it? > So set/get_parent() is never used on clkout. > > I think I just added the callbacks for completeness, should we delete them > altogether? I can't really test any of these platforms, so I'm a bit wary of making such changes myself. Feel free to send a follow-up if you think it's needed :) > The patch is probably fine as-is as well so > Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Thanks! Maxime
