[PATCH v4 2/6] clk: bcm: rpi: Add a comment about RPI_FIRMWARE_SET_CLOCK_STATE behavior

[Stefan Wahren]

Am 26.01.26 um 18:26 schrieb Maíra Canal:
> On some firmware versions, RPI_FIRMWARE_SET_CLOCK_STATE doesn't
> actually power off the clock. Document this behavior so that clock
> consumers understand they may need to set the rate to minimum before
> disabling for meaningful power savings.
>
> Suggested-by: Stefan Wahren <wahrenst at gmx.net>
> Signed-off-by: Maíra Canal <mcanal at igalia.com>
Acked-by: Stefan Wahren <wahrenst at gmx.net>

Thanks
> ---
>   drivers/clk/bcm/clk-raspberrypi.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
> index 9783385d5859836898683209e320fcc928dfdc71..2e63121af0900ac9b4874b666cf6d02baa8be11c 100644
> --- a/drivers/clk/bcm/clk-raspberrypi.c
> +++ b/drivers/clk/bcm/clk-raspberrypi.c
> @@ -308,6 +308,12 @@ static void raspberrypi_fw_unprepare(struct clk_hw *hw)
>   	u32 state = 0;
>   	int ret;
>   
> +	/*
> +	 * On some firmware versions, RPI_FIRMWARE_SET_CLOCK_STATE doesn't
> +	 * actually power off the clock. To achieve meaningful power consumption
> +	 * reduction, consumers need to set the clock rate to minimum before
> +	 * disabling it.
> +	 */
>   	ret = raspberrypi_clock_property(rpi->firmware, data,
>   					 RPI_FIRMWARE_SET_CLOCK_STATE, &state);
>   	if (ret)
>