[PATCH] i2c: muxes: pca954x: Fix broken reset-gpio usage

Krzysztof Kozlowski
2025-11-03T15:19:13Z

Revert commit 690de2902dca ("i2c: muxes: pca954x: Use reset controller
only") and its dependent commit 94c296776403 ("i2c: muxes: pca954x:
Reset if (de)select fails") because the first breaks all users of the
driver, by requiring a completely optional reset-gpio driver. These
commits cause that mux driver simply stops working when optional
reset-gpio is not included, but that reset-gpio is not pulled anyhow.

Driver cannot remove legacy reset-gpios handling.

Fixes: 690de2902dca ("i2c: muxes: pca954x: Use reset controller only")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
drivers/i2c/muxes/i2c-mux-pca954x.c | 50 +++++++++++++----------------
1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 75c8d08fa24e..b9f370c9f018 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -118,6 +118,7 @@ struct pca954x {
raw_spinlock_t lock;
struct regulator *supply;

+ struct gpio_desc *reset_gpio;
struct reset_control *reset_cont;
};

@@ -315,25 +316,6 @@ static u8 pca954x_regval(struct pca954x *data, u8 chan)
return 1 << chan;
}

-static void pca954x_reset_assert(struct pca954x *data)
-{
- if (data->reset_cont)
- reset_control_assert(data->reset_cont);
-}
-
-static void pca954x_reset_deassert(struct pca954x *data)
-{
- if (data->reset_cont)
- reset_control_deassert(data->reset_cont);
-}
-
-static void pca954x_reset_mux(struct pca954x *data)
-{
- pca954x_reset_assert(data);
- udelay(1);
- pca954x_reset_deassert(data);
-}
-
static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
struct pca954x *data = i2c_mux_priv(muxc);
@@ -347,8 +329,6 @@ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
ret = pca954x_reg_write(muxc->parent, client, regval);
data->last_chan = ret < 0 ? 0 : regval;
}
- if (ret == -ETIMEDOUT && data->reset_cont)
- pca954x_reset_mux(data);

return ret;
}
@@ -358,7 +338,6 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
struct pca954x *data = i2c_mux_priv(muxc);
struct i2c_client *client = data->client;
s32 idle_state;
- int ret = 0;

idle_state = READ_ONCE(data->idle_state);
if (idle_state >= 0)
@@ -368,10 +347,8 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
if (idle_state == MUX_IDLE_DISCONNECT) {
/* Deselect active channel */
data->last_chan = 0;
- ret = pca954x_reg_write(muxc->parent, client,
- data->last_chan);
- if (ret == -ETIMEDOUT && data->reset_cont)
- pca954x_reset_mux(data);
+ return pca954x_reg_write(muxc->parent, client,
+ data->last_chan);
}

/* otherwise leave as-is */
@@ -550,10 +527,29 @@ static int pca954x_get_reset(struct device *dev, struct pca954x *data)
if (IS_ERR(data->reset_cont))
return dev_err_probe(dev, PTR_ERR(data->reset_cont),
"Failed to get reset\n");
+ else if (data->reset_cont)
+ return 0;
+
+ /*
+ * fallback to legacy reset-gpios
+ */
+ data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(data->reset_gpio)) {
+ return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
+ "Failed to get reset gpio");
+ }

return 0;
}

+static void pca954x_reset_deassert(struct pca954x *data)
+{
+ if (data->reset_cont)
+ reset_control_deassert(data->reset_cont);
+ else
+ gpiod_set_value_cansleep(data->reset_gpio, 0);
+}
+
/*
* I2C init/probing/exit functions
*/
@@ -593,7 +589,7 @@ static int pca954x_probe(struct i2c_client *client)
if (ret)
goto fail_cleanup;

- if (data->reset_cont) {
+ if (data->reset_cont || data->reset_gpio) {
udelay(1);
pca954x_reset_deassert(data);
/* Give the chip some time to recover. */
--
2.48.1