Re: [PATCH 6/6] regulator: qcom_smd: Add support to define the bootup voltage

[Devi Priya]

On 1/27/2023 9:40 PM, Konrad Dybcio wrote:
> On 27.01.2023 17:07, Devi Priya wrote:
> > On 1/13/2023 9:07 PM, Konrad Dybcio wrote:
> > > On 13.01.2023 16:03, devi priya wrote:
> > > > Kernel does not know the initial voltage set by the bootloaders.
> > > > During regulator registration, the voltage variable is just declared
> > > > and it is zero. Based on that, the regulator framework considers current
> > > > the voltage as zero and tries to bring up each regulator to minimum
> > > > the supported voltage.
> > > >
> > > > This introduces a dip in the voltage during kernel boot and gets
> > > > stabilized once the voltage scaling comes into picture.
> > > >
> > > > To avoid the voltage dip, adding support to define the
> > > > bootup voltage set by the boodloaders and based on it, regulator
> > > > framework understands that proper voltage is already set
> > > >
> > > > Co-developed-by: Praveenkumar I <quic_ipkumar@xxxxxxxxxxx>
> > > > Signed-off-by: Praveenkumar I <quic_ipkumar@xxxxxxxxxxx>
> > > > Signed-off-by: devi priya <quic_devipriy@xxxxxxxxxxx>
> > > > ---
> > > Or maybe hook it up to the spmi_regulator_common_get_voltage()
> > > from the SPMI regulator driver and read the real voltage instead
> > > of relying on hardcoded values thay may differ between boards?
> > >
> > > Konrad
> > In IPQ9574, SPMI regulator is not used. We are using RPM-Glink communication and the regulators are controlled by RPM.
> > In this case, we don't have an option to readback the bootup voltage and so, we have hardcoded the values
> Unless something changed, RPM regulator framework is simply a
> fancy front-end for communicating with the PMIC over SPMI, AFAIK..
>
> Konrad
Currently in our driver, the voltage write request will be sent to RPM 
via GLINK which then writes it to the PMIC over I2C using the below APIs
qcom_rpm_smd_write -> rpmsg_send
In IPQ9574, we do not have SPMI support or the support to readback voltage.

> > > >    drivers/regulator/qcom_smd-regulator.c | 6 +++++-
> > > >    1 file changed, 5 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/regulator/qcom_smd-regulator.c b/drivers/regulator/qcom_smd-regulator.c
> > > > index 1eb17d378897..49a36b07397c 100644
> > > > --- a/drivers/regulator/qcom_smd-regulator.c
> > > > +++ b/drivers/regulator/qcom_smd-regulator.c
> > > > @@ -800,6 +800,7 @@ struct rpm_regulator_data {
> > > >        u32 id;
> > > >        const struct regulator_desc *desc;
> > > >        const char *supply;
> > > > +    int boot_uV; /* To store the bootup voltage set by bootloaders */
> > > >    };
> > > >      static const struct rpm_regulator_data rpm_mp5496_regulators[] = {
> > > > @@ -809,7 +810,7 @@ static const struct rpm_regulator_data rpm_mp5496_regulators[] = {
> > > >    };
> > > >      static const struct rpm_regulator_data rpm_ipq9574_mp5496_regulators[] = {
> > > > -    { "s1", QCOM_SMD_RPM_SMPA, 1, &ipq9574_mp5496_smpa1, "s1" },
> > > > +    { "s1", QCOM_SMD_RPM_SMPA, 1, &ipq9574_mp5496_smpa1, "s1", 875000 },
> > > >        {}
> > > >    };
> > > >    @@ -1394,6 +1395,9 @@ static int rpm_regulator_init_vreg(struct qcom_rpm_reg *vreg, struct device *dev
> > > >        vreg->type    = rpm_data->type;
> > > >        vreg->id    = rpm_data->id;
> > > >    +    if (rpm_data->boot_uV)
> > > > +        vreg->uV = rpm_data->boot_uV;
> > > > +
> > > >        memcpy(&vreg->desc, rpm_data->desc, sizeof(vreg->desc));
> > > >        vreg->desc.name = rpm_data->name;
> > > >        vreg->desc.supply_name = rpm_data->supply;
> > Best Regards,
> > Devi Priya
Best Regards,
Devi Priya