Hi! On the raspberry pi the pcm (and other) clock has multiple parent clocks that the driver may select from to get the "best fit" clock. This list of parents of valid for each clock is hard-coded in the driver. But this "standard" list of parents includes some clocks that are independently controlled by the firmware with - unfortunately for now - no notification of changes going back to the linux kernel. This is mostly needed for powermanagement and ARM clock modifications as well as to avoid overheating. So how is the best way to define those parent clocks one wants to use for an individual clock? As far as I can tell none of the default dt-properties really fit. So I wonder if something like the following would be acceptable: cprman: cprman@7e101000 { compatible = "brcm,bcm2835-cprman"; #clock-cells = <1>; reg = <0x7e101000 0x2000>; clocks = <&clk_osc>; /* limit parent clock selection for the PCM clock */ pcm_clk@BCM2835_CLOCK_PCM { reg = <BCM2835_CLOCK_PCM>; clock-parent-names = "gnd", "xosc", "plla_per", "plld_per"; }; }; As an alternative it could also be defined on the consumer side: i2s: i2s@7e203000 { compatible = "brcm,bcm2835-i2s"; reg = <0x7e203000 0x24>; clocks = <&cprman BCM2835_CLOCK_PCM>; clock-parent-names = "gnd", "xosc", "plla_per", "plld_per"; }; This variant might need to be made "clock-parent-names-0", "clock-parent-names-1", ... (analogous to "pinctrl-0") to allow distinct parents for distinct clocks. Is something like this acceptable? If not, what approach could be taken to achieve the required (except for hard-coding the selection it in the driver)? If it is the second, then I guess the implementation would need to go into the core framework while for the first the logic could also stay within the driver. Thanks, Martin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html