[PATCH RFC 5/6] riscv: dts: thead: Add PVT node

[Michal Wilczynski]

On 5/27/25 10:00, Drew Fustini wrote:
> On Sat, May 24, 2025 at 11:14:59PM +0200, Michal Wilczynski wrote:
>> Add PVT DT node for thermal sensor.
>>
>> Signed-off-by: Michal Wilczynski <m.wilczynski at samsung.com>
>> ---
>>  arch/riscv/boot/dts/thead/th1520.dtsi | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
>> index f24e12d7259fabcfbdc2dfa966d759db06684ab4..faf5c3aaf209b24cd99ddc377a88e08a8cce24fe 100644
>> --- a/arch/riscv/boot/dts/thead/th1520.dtsi
>> +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
>> @@ -648,6 +648,17 @@ padctrl_aosys: pinctrl at fffff4a000 {
>>  			thead,pad-group = <1>;
>>  		};
>>  
>> +		pvt: pvt at fffff4e000 {
>> +			compatible = "moortec,mr75203";
>> +			reg = <0xff 0xfff4e000 0x0 0x80>,
>> +			      <0xff 0xfff4e080 0x0 0x100>,
>> +			      <0xff 0xfff4e180 0x0 0x680>,
>> +			      <0xff 0xfff4e800 0x0 0x600>;
>> +			reg-names = "common", "ts", "pd", "vm";
>> +			clocks = <&aonsys_clk>;
>> +			#thermal-sensor-cells = <1>;
>> +		};
>> +
>>  		gpio at fffff52000 {
>>  			compatible = "snps,dw-apb-gpio";
>>  			reg = <0xff 0xfff52000 0x0 0x1000>;
>>
>> -- 
>> 2.34.1
>>
> 
> I found that on my lpi4a that boot while hang after applying this patch.
> I think that it is related to clocks as boot finished okay when using
> clk_ignore_unused on the kernel cmdline. Do you happen have that in your
> kernel cmdline?
> 
> I need to investigate further to understand which clocks are causing the
> problem.
> 
> Thanks,
> Drew
> 

Thanks for your earlier message. I've investigated, and you were right
about the clocks – the specific one causing the hang is CLK_CPU2AON_X2H.

This appears to be an AHB bus clock required for CPU access to the AON
domain. My proposed solution is to make the pvt node a child of a new
parent bus node in the Device Tree. This new "AON bus" node would then
explicitly request and manage CLK_CPU2AON_X2H, ensuring it's enabled
when its children are accessed.

What are your thoughts on this approach?

Best regards,
-- 
Michal Wilczynski <m.wilczynski at samsung.com>