Hi Quentin,
On 2024-04-02 16:44, Quentin Schulz wrote:
Hi Jonas,
On 3/31/24 22:28, Jonas Karlman wrote:
rk3399-nanopi-4.dtsi try to set parent of and set rate to 100 MHz of the SCLK_PCIEPHY_REF clock.
The existing enable/disable ops for SCLK_PCIEPHY_REF already handles setting correct parent once the clock gets enabled. And 100 MHz is the default rate used for this clock.
I'm not sure that's true?
If I read the TRM correctly, clk_pciephy_ref_sel can come either from clk_pcie_ref24m (the default) or clk_pcie_ref100m.
enable/disable is actually only ever writing 0 to that bit (bit 10 in CRU_CLKSEL_CON18) and not even enabling the clock.
You are correct, I should have looked closer at the code :-)
Assuming clk_pcie_ref24m is the 24MHz base clock (which seems to be the case according to the Linux kernel CRU driver), there shouldn't be a way to disable that clock. However, if clk_pcie_ref100m is selected, one needs to enable/disable it via CRU_CLKGATE_CON12 bit 6 (enabled by default).
set_parent should be properly implemented to handle this parenting and enable/disable fixed to use the proper register.
For v2 I have added improved support for enable/disable, setting parent and rate of the pciephy refclk, it is not a full implementation but should support the state of updated device tree files.
I have not been able to runtime test on a nanopi-4 based board yet, but will include the updated version in v2, it does not seem to affect any of my other boards not setting parent/rate.
Regards, Jonas
Cheers, Quentin