regulator: core: Add option to prevent disabling unused regulators

This may be useful for debugging and develompent purposes, when there are
drivers that depend on regulators to be enabled but do not request them.

It is inspired from the clk_ignore_unused and pd_ignore_unused parameters,
that are used to keep firmware-enabled clocks and power domains on even if
these are not used by drivers.

The parameter is not expected to be used in normal cases and should not be
needed on a platform with proper driver support.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20231107190926.1185326-1-javierm@redhat.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 65731b060e3fef98cb97f03695ca8757ee197700..825159394da2aa3e077388ed0a64ef601310b28d 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5544,6 +5544,13 @@
                        print every Nth verbose statement, where N is the value
                        specified.
 
+       regulator_ignore_unused
+                       [REGULATOR]
+                       Prevents regulator framework from disabling regulators
+                       that are unused, due no driver claiming them. This may
+                       be useful for debug and development, but should not be
+                       needed on a platform with proper driver support.
+
        relax_domain_level=
                        [KNL, SMP] Set scheduler's default relax_domain_level.
                        See Documentation/admin-guide/cgroup-v1/cpusets.rst.

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 3137e40fcd3e0586a81b1626304ab955a87695d4..79777495cc3a0366ea2dab2a45bbffb3d08c1093 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -6234,6 +6234,14 @@ unlock:
        return 0;
 }
 
+static bool regulator_ignore_unused;
+static int __init regulator_ignore_unused_setup(char *__unused)
+{
+       regulator_ignore_unused = true;
+       return 1;
+}
+__setup("regulator_ignore_unused", regulator_ignore_unused_setup);
+
 static void regulator_init_complete_work_function(struct work_struct *work)
 {
        /*
@@ -6246,6 +6254,15 @@ static void regulator_init_complete_work_function(struct work_struct *work)
        class_for_each_device(&regulator_class, NULL, NULL,
                              regulator_register_resolve_supply);
 
+       /*
+        * For debugging purposes, it may be useful to prevent unused
+        * regulators from being disabled.
+        */
+       if (regulator_ignore_unused) {
+               pr_warn("regulator: Not disabling unused regulators\n");
+               return;
+       }
+
        /* If we have a full configuration then disable any regulators
         * we have permission to change the status for and which are
         * not in use or always_on.  This is effectively the default