On 17.02.2023 15:20, 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>
> ---
Thinking about it again, this seems like something that could be
generalized and introduced into regulator core.. Hardcoding this
will not end well.. Not to mention it'll affect all mp5496-using
boards that are already upstream.
WDYT about regulator-init-microvolts Mark?
Konrad
> Changes in V2:
> - Added the bootup voltages to s2 and l2 regulators
>
> drivers/regulator/qcom_smd-regulator.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/regulator/qcom_smd-regulator.c b/drivers/regulator/qcom_smd-regulator.c
> index a40e66cea7e7..5f9fe6b9d368 100644
> --- a/drivers/regulator/qcom_smd-regulator.c
> +++ b/drivers/regulator/qcom_smd-regulator.c
> @@ -800,12 +800,13 @@ 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[] = {
> - { "s1", QCOM_SMD_RPM_SMPA, 1, &mp5496_smpa1, "s1" },
> - { "s2", QCOM_SMD_RPM_SMPA, 2, &mp5496_smpa2, "s2" },
> - { "l2", QCOM_SMD_RPM_LDOA, 2, &mp5496_ldoa2, "l2" },
> + { "s1", QCOM_SMD_RPM_SMPA, 1, &mp5496_smpa1, "s1", 875000 },
> + { "s2", QCOM_SMD_RPM_SMPA, 2, &mp5496_smpa2, "s2", 875000 },
> + { "l2", QCOM_SMD_RPM_LDOA, 2, &mp5496_ldoa2, "l2", 2950000 },
> {}
> };
>
> @@ -1388,6 +1389,9 @@ 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;
