Message-Id: <20251110-s2mpg1x-regulators-v4-8-94c9e726d4ba@linaro.org>
Date: Mon, 10 Nov 2025 19:28:51 +0000
From: André Draszik <andre.draszik@...aro.org>
To: Tudor Ambarus <tudor.ambarus@...aro.org>, Rob Herring <robh@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>, 
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
 Lee Jones <lee@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, 
 Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
 linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-gpio@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH v4 08/20] mfd: sec-common: Instantiate s2mpg10 bucks and
 ldos separately

Bucks can conceivably be used as supplies for LDOs, but currently it
can be impossible to mark BUCKs as LDO supplies. This becomes
particularly an issue with the upcoming support for the S2MPG11 PMIC.

The typical use of the S2MPG10 PMIC is in combination with an S2MPG11
PMIC in a main/sub configuration. Bucks of one are usually used as
supplies for LDOs of either itself or of the other: several S2MPG10
LDOs are consumers of various S2MPG10 bucks & S2MPG11 bucks, and
several S2MPG11 LDOs are supplied by various S2MPG10 bucks & S2MPG11
bucks.

So we have a circular dependency here - LDOs (and potentially also
bucks) of one PMIC depend on bucks of the other.

This means that if all S2MPG10 rails are handled by the same instance
of the S2MPG10 regulator driver, probe of all rails will defer, because
the supplies to the LDOs can not be resolved during probe. The same
goes for S2MPG11.

The result is that neither driver can probe successfully and probe will
ultimately fail. In other words it's currently impossible to mark BUCKs
as LDO supplies.

Additionally, multiple (LDO-) rails may share the same (buck) supply
rail and some of these LDOs might supply important consumers, e.g. RAM.
To stay with RAM, if one of those consumers needs to defer probe before
the rail supplying RAM has probed, the shared (buck) supply gets
disabled and the whole system comes to a halt, since Linux hasn't seen
the DDR-supplying rail yet, and hasn't had a chance to mark the buck
rail as having another consumer.

By splitting all rails into separate driver instances, the circular
dependency is gone, each individual instance can probe when its supplies
are ready. This approach also solves the multiple-consumers-on-one-rail
issue during probe.

The mfd_cell's ::id field is used to inform the regulator driver which
regulator to instantiate.

Signed-off-by: André Draszik <andre.draszik@...aro.org>

---
v3:
- one instance per actual rail, not per rail type (LDO or buck)
- more descriptive commit message

v2:
- fix commit message typos: s2mp1 -> s2mpg1
---
 drivers/mfd/sec-common.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/sec-common.c b/drivers/mfd/sec-common.c
index 42d55e70e34c8d7cd68cddaecc88017e259365b4..b722481594801e545d24014af6afd5e1e39d7522 100644
--- a/drivers/mfd/sec-common.c
+++ b/drivers/mfd/sec-common.c
@@ -14,6 +14,7 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/samsung/core.h>
 #include <linux/mfd/samsung/irq.h>
+#include <linux/mfd/samsung/s2mpg10.h>
 #include <linux/mfd/samsung/s2mps11.h>
 #include <linux/mfd/samsung/s2mps13.h>
 #include <linux/module.h>
@@ -35,7 +36,47 @@ static const struct mfd_cell s2dos05_devs[] = {
 
 static const struct mfd_cell s2mpg10_devs[] = {
 	MFD_CELL_NAME("s2mpg10-meter"),
-	MFD_CELL_NAME("s2mpg10-regulator"),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK1),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK2),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK3),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK4),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK5),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK6),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK7),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK8),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK9),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_BUCK10),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO1),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO2),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO3),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO4),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO5),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO6),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO7),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO8),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO9),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO10),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO11),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO12),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO13),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO14),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO15),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO16),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO17),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO18),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO19),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO20),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO21),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO22),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO23),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO24),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO25),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO26),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO27),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO28),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO29),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO30),
+	MFD_CELL_BASIC("s2mpg10-regulator", NULL, NULL, 0, S2MPG10_LDO31),
 	MFD_CELL_NAME("s2mpg10-rtc"),
 	MFD_CELL_OF("s2mpg10-clk", NULL, NULL, 0, 0, "samsung,s2mpg10-clk"),
 	MFD_CELL_OF("s2mpg10-gpio", NULL, NULL, 0, 0, "samsung,s2mpg10-gpio"),

-- 
2.51.2.1041.gc1ab5b90ca-goog

Powered by blists - more mailing lists