Re: [PATCH] arm64: dts: qcom: sm8750-mtp: Set sufficient voltage for panel nt37801

[Ayushi Makhija]

On 3/26/2026 9:28 PM, Bjorn Andersson wrote:
> On Thu, Mar 26, 2026 at 03:06:52PM +0530, Ayushi Makhija wrote:
>> On 3/24/2026 7:34 AM, Bjorn Andersson wrote:
>>> On Mon, Mar 23, 2026 at 03:52:29PM +0530, Ayushi Makhija wrote:
>>>> The NT37801 Sepc V1.0 chapter "5.7.1 Power On Sequence" states
>>>> VDDI=1.65V~1.95V, so set sufficient voltage for panel nt37801.
>>>>
>>>
>>> Please add Fixes: tag.
>>>
>>
>> Hi Bjorn,
>>
>> Sure, will add in new patchset.
>>
>>>> Signed-off-by: Ayushi Makhija <quic_amakhija@xxxxxxxxxxx>
>>>
>>> Please start using your oss.qualcomm.com address.
>>>
>>>> ---
>>>>  arch/arm64/boot/dts/qcom/sm8750-mtp.dts | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/sm8750-mtp.dts b/arch/arm64/boot/dts/qcom/sm8750-mtp.dts
>>>> index 3837f6785320..6ba4e69bf377 100644
>>>> --- a/arch/arm64/boot/dts/qcom/sm8750-mtp.dts
>>>> +++ b/arch/arm64/boot/dts/qcom/sm8750-mtp.dts
>>>> @@ -462,7 +462,7 @@ vreg_l11b_1p0: ldo11 {
>>>>  
>>>>  		vreg_l12b_1p8: ldo12 {
>>>>  			regulator-name = "vreg_l12b_1p8";
>>>> -			regulator-min-microvolt = <1200000>;
>>>> +			regulator-min-microvolt = <1650000>;
>>>
>>> Are you sure it's not supposed to be 1.8V, given the name of the rail?
>>>
>>> Regards,
>>> Bjorn
>>
>> There was already discussion regarding the minimum voltage for this regulator on sm8550 target
>> on other upstream patch. 
>>
>> Link: https://lore.kernel.org/all/aQQdQoCLeKhYtY7W@xxxxxxxxxxxxxxxxxxxxxxxx/
>>
>> This values is according to the NT37801 panel sec
>> "The NT37801 Sepc V1.0 chapter "5.7.1 Power On Sequence" states 
>> VDDI=1.65V~1.95V."
>>
> 
> Yes, so the panel requires 1.65V, so regulator-min-microvolt needs to be
> at least that. But regulator-min-microvolt should account for all the
> consumers of the rail, are there any others?
> 
> Which leads me to my question, the people designing the board named the
> rail VREG_L12B_1P8 in the schematics, why didn't they name it
> VREG_L12B_1P65?
> 
> Please check all the consumers and make the regulator-min-microvolt work
> for all of them - if that's 1.65V, then your change is good.
> 
> Regards,
> Bjorn

Hi Bjorn,

There is only one consumer of VREG_L12B_1P8 rail, i.e. NT37801 panel.
So regulator-min-microvolt as 1.65V should be fine for VREG_L12B_1P8 rail.

Thanks,
Ayushi