linux-kernel - [PATCH RFC 2/2] regulator: qcom_smd: Disable unused regulators

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Message-Id: <20231004-reg-smd-unused-v1-2-5d682493d555@kernkonzept.com>
Date:   Wed, 04 Oct 2023 16:17:18 +0200
From:   Stephan Gerhold <stephan.gerhold@...nkonzept.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Stephan Gerhold <stephan@...hold.net>,
        Stephan Gerhold <stephan.gerhold@...nkonzept.com>
Subject: [PATCH RFC 2/2] regulator: qcom_smd: Disable unused regulators

The RPM firmware on Qualcomm platforms does not provide a way to check
if a regulator is on during boot using the SMD interface. If the
regulators are already on during boot and Linux does not make use of
them they will currently stay enabled forever. The regulator core does
not know these regulators are on and cannot clean them up together with
the other unused regulators.

Fix this by setting the initial enable state to -EINVAL similar to
qcom-rpmh-regulator.c. The regulator core will then also explicitly
disable all unused regulators with unknown status.

Signed-off-by: Stephan Gerhold <stephan.gerhold@...nkonzept.com>
---
NOTE: This has a slight potential of breaking boards that rely on having
unused regulators permanently enabled (without regulator-always-on).
However, this is always a mistake in the device tree so it's probably
better to risk some breakage now, add the missing regulators and avoid
this problem for all future boards.
---
 drivers/regulator/qcom_smd-regulator.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/qcom_smd-regulator.c b/drivers/regulator/qcom_smd-regulator.c
index f53ada076252..0bbfba2e17ff 100644
--- a/drivers/regulator/qcom_smd-regulator.c
+++ b/drivers/regulator/qcom_smd-regulator.c
@@ -53,14 +53,14 @@ static int rpm_reg_write_active(struct qcom_rpm_reg *vreg)
 		reqlen++;
 	}
 
-	if (vreg->uv_updated && vreg->is_enabled) {
+	if (vreg->uv_updated && vreg->is_enabled > 0) {
 		req[reqlen].key = cpu_to_le32(RPM_KEY_UV);
 		req[reqlen].nbytes = cpu_to_le32(sizeof(u32));
 		req[reqlen].value = cpu_to_le32(vreg->uV);
 		reqlen++;
 	}
 
-	if (vreg->load_updated && vreg->is_enabled) {
+	if (vreg->load_updated && vreg->is_enabled > 0) {
 		req[reqlen].key = cpu_to_le32(RPM_KEY_MA);
 		req[reqlen].nbytes = cpu_to_le32(sizeof(u32));
 		req[reqlen].value = cpu_to_le32(vreg->load / 1000);
@@ -1377,6 +1377,7 @@ static int rpm_regulator_init_vreg(struct qcom_rpm_reg *vreg, struct device *dev
 	vreg->rpm	= rpm;
 	vreg->type	= rpm_data->type;
 	vreg->id	= rpm_data->id;
+	vreg->is_enabled = -EINVAL;
 
 	memcpy(&vreg->desc, rpm_data->desc, sizeof(vreg->desc));
 	vreg->desc.name = rpm_data->name;

-- 
2.39.2