On Sat, 27 Jan 2024 at 00:19, André Draszik [off-list ref] wrote:

CMU_PERIC1 is the clock management unit used for the peric1 block which
is used for additional USI, I3C and PWM interfaces/busses. Add support
for muxes, dividers and gates of cmu_peric1, except for
CLK_GOUT_PERIC1_IP which isn't well described in the datasheet and
which downstream also ignores (similar to cmu_peric0).

Two clocks have been marked as CLK_IS_CRITICAL for the following
reason:
    * disabling them makes it impossible to access any peric1
      registers, (including those two registers).
    * disabling gout_peric1_lhm_axi_p_peric1_i_clk sometimes has the
      additional effect of making the whole system unresponsive.

The clocks marked as CLK_IGNORE_UNUSED need to be kept on until we have
updated the respective drivers for the following reasons:
    * gout_peric1_gpio_peric1_pclk is required by the pinctrl
      configuration. With this clock disabled, reconfiguring the pins
      (for USI/I2C, USI/UART) will hang during register access.
      Since pingctrl-samsung doesn't support a clock at the moment, we
      just keep the kernel from disabling it at boot, until we have an
      update for samsung-pinctrl, at which point we'll drop the flag.
    * gout_peric1_sysreg_peric1_pclk needs to be hooked up to
      sysreg_peric1 in DT which will be done in a followup-patch, at
      which point we'll drop the special treatment from here. We're
      adding the flag temporarily here so as to not break the boot (due
      to pclk otherwise getting disabled).

Signed-off-by: André Draszik <andre.draszik@linaro.org>

---

Thankyou for being verbose on this reasoning behind CLK_IGNORE_UNUSED
and CLK_IS_CRITICAL flags

Reviewed-by: Peter Griffin <peter.griffin@linaro.org>

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