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

[Bjorn Andersson]

On Thu, Apr 09, 2026 at 11:14:10AM +0530, Ayushi Makhija wrote:
> 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.
> 

Had to look it up myself. MTP power grid says it should be 1.8V.

Thank you,
Bjorn

> Thanks,
> Ayushi
>