On 2/16/25 10:12 AM, Artur Weber wrote:
This patchset does the following: - Introduce support for bus clocks. These are fairly similar to peripheral clocks, but only implement policy, gate and hyst. - Introduce support for prerequisite clocks; this way we can make peripheral clocks automatically enable their corresponding bus clocks. - Add matching bus clocks for BCM21664 peripheral clocks and update device tree bindings to match. The prerequisite clock portion of this patchset is adapted from an older attempt to add bus clocks[1], submitted by Alex Elder. I've retained his authorship on that commit.
That was a long time ago!
Notably, Alex's patchset moved clock initialization to the prepare function. This seems to be incorrect; the prepare function gets called before the enable function, but not before "set rate"/"set parent" functions; thus, while clocks enabled fine, any configuration done before they were first enabled was broken. I ignored that part of the patchset and only kept the prerequisite clocks.
I think you're right.
I would appreciate feedback on the prerequisite clock patch, hence why this patchset is marked as RFC. I wasn't able to find any other driver that does something like this, so I'm not sure if it's correct (especially since I had to switch from non-locking __clk_prepare and __clk_enable to the regular locking versions, as the non-locking versions are no longer public - they appear to have been replaced by clk_core counterparts, but those functions are not exported anywhere AFAICT). An alternative way to do this dependency would be to wrap every component with a relevant bus clock in a "simple-pm-bus" node with the bus clock in DT, but this seems rather unwieldy.
Yes I had the same thought, and ask about this on patch 3. I can't comment on whether this notion of a prerequisite (that is not its parent) makes sense though. I didn't look at patch 1 or patch 5. -Alex
[1] https://lore.kernel.org/lkml/1402926007-4436-1-git-send-email-elder@xxxxxxxxxx/ Signed-off-by: Artur Weber <aweber.kernel@xxxxxxxxx> --- Alex Elder (1): clk: bcm281xx: implement prerequisite clocks Artur Weber (4): dt-bindings: clock: brcm,kona-ccu: Add BCM21664 bus clocks clk: bcm: kona: Add support for bus clocks clk: bcm21664: Add matching bus clocks for peripheral clocks ARM: dts: bcm2166x-common: Add matching bus clocks for peripheral clocks .../devicetree/bindings/clock/brcm,kona-ccu.yaml | 18 ++- arch/arm/boot/dts/broadcom/bcm2166x-common.dtsi | 28 +++-- drivers/clk/bcm/clk-bcm21664.c | 107 ++++++++++++++++-- drivers/clk/bcm/clk-kona-setup.c | 116 +++++++++++++++++++ drivers/clk/bcm/clk-kona.c | 124 ++++++++++++++++++++- drivers/clk/bcm/clk-kona.h | 30 ++++- include/dt-bindings/clock/bcm21664.h | 19 +++- 7 files changed, 411 insertions(+), 31 deletions(-) --- base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04 change-id: 20250212-kona-bus-clock-4297eefae940 Best regards,
