linux-kernel - [PATCH V2 4/6] regulator: qcom_smd: Add support to define the bootup voltage

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Date:   Fri, 17 Feb 2023 19:50:28 +0530
From:   Devi Priya <quic_devipriy@...cinc.com>
To:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <lgirdwood@...il.com>,
        <broonie@...nel.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
CC:     <quic_srichara@...cinc.com>, <quic_gokulsri@...cinc.com>,
        <quic_sjaganat@...cinc.com>, <quic_kathirav@...cinc.com>,
        <quic_arajkuma@...cinc.com>, <quic_anusha@...cinc.com>,
        <quic_ipkumar@...cinc.com>
Subject: [PATCH V2 4/6] regulator: qcom_smd: Add support to define the bootup voltage

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@...cinc.com>
Signed-off-by: Praveenkumar I <quic_ipkumar@...cinc.com>
Signed-off-by: Devi Priya <quic_devipriy@...cinc.com>
---
 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;
-- 
2.17.1