[PATCH v2 4/7] i2c: of-prober: Defer regulator_disable() on successful probe in simple helper
From: Chen-Yu Tsai <wenst@chromium.org>
Date: 2026-07-03 11:56:24
Also in:
chrome-platform, linux-arm-kernel, linux-devicetree, linux-i2c, linux-mediatek, lkml
Subsystem:
i2c of component prober, i2c subsystem, the rest · Maintainers:
Chen-Yu Tsai, Andi Shyti, Linus Torvalds
When a I2C component is found, it's device node is immediately enabled. This triggers device creation and driver binding. The prober will hold the regulator enable reference across this part. If the driver probes synchronously, then it happens within this window. On the other hand, if the driver probes asynchronously, there is high chance that it happens after the prober's cleanup function was called, in which case the regulator would have been disabled when the driver's probe function is called. This would then require the driver to wait 100 ms for the hardware to reinitialize, even if the probe function was just a split second late and the regulator was disabled a few milliseconds ago. Recently, some of the drivers for the component that are targeted by the I2C OF component prober gained the ability to skip waiting for hardware initialization if the regulator was left enabled. This happens when the PMIC has them on by default, or if the component prober left them on after probing the component. Wait a bit of time before dropping the enable refcount on our end so that the actual driver has the opportunity to catch and increase the refcount on their end. The 100 ms delay was arbitrarily chosen. Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> --- drivers/i2c/i2c-core-of-prober.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/i2c-core-of-prober.c b/drivers/i2c/i2c-core-of-prober.c
index f274e260353c..17495125467e 100644
--- a/drivers/i2c/i2c-core-of-prober.c
+++ b/drivers/i2c/i2c-core-of-prober.c@@ -243,11 +243,23 @@ static int i2c_of_probe_simple_enable_regulator(struct device *dev, struct i2c_o return 0; } -static void i2c_of_probe_simple_disable_regulator(struct device *dev, struct i2c_of_probe_simple_ctx *ctx) +static void i2c_of_probe_simple_disable_regulator(struct device *dev, + struct i2c_of_probe_simple_ctx *ctx, + bool defer_disable) { if (!ctx->supply) return; + /* + * Wait a bit of time for async drivers to probe and increase the + * regulator enable count. This allows the drivers to check and + * skip waiting for re-initialization. + */ + if (defer_disable) { + dev_dbg(dev, "Deferring regulator disable\n"); + msleep(100); + } + dev_dbg(dev, "Disabling regulator supply \"%s\"\n", ctx->opts->supply_name); regulator_disable(ctx->supply);
@@ -364,7 +376,7 @@ int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, return 0; out_disable_regulator: - i2c_of_probe_simple_disable_regulator(dev, ctx); + i2c_of_probe_simple_disable_regulator(dev, ctx, false); out_put_gpiod: i2c_of_probe_simple_put_gpiod(ctx); out_put_supply:
@@ -409,7 +421,7 @@ void i2c_of_probe_simple_cleanup(struct device *dev, void *data) i2c_of_probe_simple_disable_gpio(dev, ctx); i2c_of_probe_simple_put_gpiod(ctx); - i2c_of_probe_simple_disable_regulator(dev, ctx); + i2c_of_probe_simple_disable_regulator(dev, ctx, true); i2c_of_probe_simple_put_supply(ctx); } EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_cleanup, "I2C_OF_PROBER");
--
2.55.0.rc0.799.gd6f94ed593-goog