Re: [PATCH] arm64: dts: qcom: sc8280xp-huawei-gaokun3: Add dsi panel DT node

[Konrad Dybcio]

On 6/30/26 12:41 PM, Pengyu Luo wrote:
> On Tue, Jun 30, 2026 at 6:34 PM Konrad Dybcio
> <konrad.dybcio@xxxxxxxxxxxxxxxx> wrote:
>>
>> On 6/30/26 12:30 PM, Pengyu Luo wrote:
>>> On Tue, Jun 30, 2026 at 6:29 PM Konrad Dybcio
>>> <konrad.dybcio@xxxxxxxxxxxxxxxx> wrote:
>>>>
>>>> On 6/30/26 11:28 AM, Pengyu Luo wrote:
>>>>> On Tue, Jun 30, 2026 at 5:18 PM Konrad Dybcio
>>>>> <konrad.dybcio@xxxxxxxxxxxxxxxx> wrote:
>>>>>>
>>>>>> On 6/30/26 6:22 AM, Pengyu Luo wrote:
>>>>>>> DSI panel driver have been added for a while, so add the DT node to
>>>>>>> enable it. vdd{a,s}-supply for dsi, dsi_phy are blank since the DSDT
>>>>>>> describes the wrong, no impact after manual disabling these wrong
>>>>>>> supplies.
>>>>>>>
>>>>>>> Signed-off-by: Pengyu Luo <mitltlatltl@xxxxxxxxx>
>>>>>>> ---
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>> +&mdss0_dsi0 {
>>>>>>> +     /* real vdda is unknown */
>>>>>>> +
>>>>>>
>>>>>> L3B: DSI core 1.2 V (both?)
>>>>>> L6B: DSI0/1 PLL and core 0.9 V
>>>>>>
>>>>>
>>>>> Yes, that is what I saw in the DSDT, however, I can disable them
>>>>> safely (hack the regulator driver to add a sysfs to handle these
>>>>> regulators), the panel works well.
>>>>
>>>> L3B additionally powers CSIPHY2/3, EDP0/1, REFGEN (probably why it
>>>> ends up being on), UFSPHY and USB1_PHY
>>>>
>>>> L6B additionally powers the same components, minus refgen and USB
>>>>
>>>
>>> No, I confirmed they are totally disabled, since there is a way to check it now.
>>> https://lore.kernel.org/linux-arm-msm/20260420-read-rpmh-v3-v4-0-70c152e6c958@xxxxxxxxxxxxxxxx/
>>
>> This presents you with the status of the votes casted by HLOS, not
>> the actual hardware state
>>
> 
> If so, non-HLOS will vote on some critical regulators to keep them on,
> IIRC, once I disabled L9D, system reseted immediately.

NHLOS will generally ensure that the hardware that it needs is
powered. This does not extend to hardware that *you* may want to
access in Linux (or which was left online by UEFI), which I suspect
was the case here

>> To get the latter, you'd have to dump the SPMI registers
>>
> I will appreciate it if you provide more information.

Take a look at drivers/regulator/qcom_spmi-regulator.c, you can get
the actual live value of the enable register and the voltage selector
for each regulator

Konrad