On 17/01/2026 04:06, Richard Acayan wrote:
A device tree compatible makes it possible for this driver to be used on
Open Firmware devices. Initialization of power-managed resources such as
the reset GPIO and voltage regulators can be specified in the device
tree and handled by the driver. Add support for this so the Pixel 3a can
use the driver.

Reviewed-by: Bryan O'Donoghue <[email protected]>
Signed-off-by: Richard Acayan <[email protected]>
---
  drivers/media/i2c/imx355.c | 116 ++++++++++++++++++++++++++++++++++---
  1 file changed, 108 insertions(+), 8 deletions(-)

diff --git a/drivers/media/i2c/imx355.c b/drivers/media/i2c/imx355.c
index 776107efe386..5a8da035ba5f 100644
--- a/drivers/media/i2c/imx355.c
+++ b/drivers/media/i2c/imx355.c
@@ -3,9 +3,13 @@
#include <linux/acpi.h>
  #include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
  #include <linux/i2c.h>
  #include <linux/module.h>
+#include <linux/of.h>
  #include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
  #include <linux/unaligned.h>
#include <media/v4l2-ctrls.h>
@@ -125,6 +129,15 @@ struct imx355 {
         * Protect access to sensor v4l2 controls.
         */
        struct mutex mutex;
+
+       struct gpio_desc *reset_gpio;
+       struct regulator_bulk_data *supplies;
+};
+
+static const struct regulator_bulk_data imx355_supplies[] = {
+       { .supply = "avdd" },
+       { .supply = "dvdd" },
+       { .supply = "dovdd" },
  };
static const struct imx355_reg imx355_global_regs[] = {
@@ -1515,6 +1528,55 @@ static const struct v4l2_subdev_internal_ops 
imx355_internal_ops = {
        .open = imx355_open,
  };
+static int imx355_power_off(struct device *dev)
+{
+       struct i2c_client *client = container_of(dev, struct i2c_client, dev);
+       struct v4l2_subdev *sd = i2c_get_clientdata(client);
+       struct imx355 *imx355 = to_imx355(sd);
+
+       gpiod_set_value_cansleep(imx355->reset_gpio, 1);
+
+       regulator_bulk_disable(ARRAY_SIZE(imx355_supplies), imx355->supplies);
+       clk_disable_unprepare(imx355->clk);
+
+       return 0;
+}
+
+static int imx355_power_on(struct device *dev)
+{
+       struct i2c_client *client = container_of(dev, struct i2c_client, dev);
+       struct v4l2_subdev *sd = i2c_get_clientdata(client);
+       struct imx355 *imx355 = to_imx355(sd);
+       int ret;
+
+       ret = clk_prepare_enable(imx355->clk);
+       if (ret) {
+               dev_err(dev, "failed to enable clocks: %d\n", ret);
+               return ret;
+       }
+
+       ret = regulator_bulk_enable(ARRAY_SIZE(imx355_supplies),
+                                   imx355->supplies);
+       if (ret) {
+               dev_err(dev, "failed to enable regulators: %d\n", ret);
+               goto error_disable_clocks;
+       }
+
+       gpiod_set_value_cansleep(imx355->reset_gpio, 1);
+       usleep_range(1000, 2000);
+       gpiod_set_value_cansleep(imx355->reset_gpio, 0);
+       usleep_range(10000, 11000);
+
+       return 0;
+
+error_disable_clocks:
+       clk_disable_unprepare(imx355->clk);
+       return ret;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(imx355_pm_ops, imx355_power_off,
+                                imx355_power_on, NULL);
+
  /* Initialize control handlers */
  static int imx355_init_controls(struct imx355 *imx355)
  {
@@ -1689,16 +1751,26 @@ static int imx355_probe(struct i2c_client *client)
                                     "external clock %lu is not supported\n",
                                     freq);
- /* Initialize subdev */
-       v4l2_i2c_subdev_init(&imx355->sd, client, &imx355_subdev_ops);
-
-       /* Check module identity */
-       ret = imx355_identify_module(imx355);
+       ret = devm_regulator_bulk_get_const(imx355->dev,
+                                           ARRAY_SIZE(imx355_supplies),
+                                           imx355_supplies,
+                                           &imx355->supplies);
        if (ret) {
-               dev_err(imx355->dev, "failed to find sensor: %d", ret);
+               dev_err_probe(imx355->dev, ret, "could not get regulators");
                goto error_probe;
        }
+ imx355->reset_gpio = devm_gpiod_get_optional(imx355->dev, "reset",
+                                                    GPIOD_OUT_HIGH);
+       if (IS_ERR(imx355->reset_gpio)) {
+               ret = dev_err_probe(imx355->dev, PTR_ERR(imx355->reset_gpio),
+                                   "failed to get gpios");
+               goto error_probe;
+       }
+
+       /* Initialize subdev */
+       v4l2_i2c_subdev_init(&imx355->sd, client, &imx355_subdev_ops);
+
        imx355->hwcfg = imx355_get_hwcfg(imx355->dev);
        if (!imx355->hwcfg) {
                dev_err(imx355->dev, "failed to get hwcfg");
@@ -1706,13 +1778,26 @@ static int imx355_probe(struct i2c_client *client)
                goto error_probe;
        }
+ ret = imx355_power_on(imx355->dev);
+       if (ret) {
+               dev_err(imx355->dev, "failed to power on sensor: %d", ret);
+               goto error_probe;
+       }
+
+       /* Check module identity */
+       ret = imx355_identify_module(imx355);
+       if (ret) {
+               dev_err(imx355->dev, "failed to find sensor: %d", ret);
+               goto error_power_off;
+       }
+
        /* Set default mode to max resolution */
        imx355->cur_mode = &supported_modes[0];
ret = imx355_init_controls(imx355);
        if (ret) {
                dev_err(imx355->dev, "failed to init controls: %d", ret);
-               goto error_probe;
+               goto error_power_off;
        }
/* Initialize subdev */
@@ -1752,6 +1837,9 @@ static int imx355_probe(struct i2c_client *client)
  error_handler_free:
        v4l2_ctrl_handler_free(imx355->sd.ctrl_handler);
+error_power_off:
+       imx355_power_off(imx355->dev);
+
  error_probe:
        mutex_destroy(&imx355->mutex);
@@ -1768,7 +1856,11 @@ static void imx355_remove(struct i2c_client *client)
        v4l2_ctrl_handler_free(sd->ctrl_handler);
pm_runtime_disable(imx355->dev);
-       pm_runtime_set_suspended(imx355->dev);
+
+       if (!pm_runtime_status_suspended(imx355->dev)) {
+               imx355_power_off(imx355->dev);
+               pm_runtime_set_suspended(imx355->dev);
+       }
mutex_destroy(&imx355->mutex);
  }
@@ -1779,10 +1871,18 @@ static const struct acpi_device_id imx355_acpi_ids[] 
__maybe_unused = {
  };
  MODULE_DEVICE_TABLE(acpi, imx355_acpi_ids);
+static const struct of_device_id imx355_match_table[] = {
+       { .compatible = "sony,imx355", },
+       { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx355_match_table);
+
  static struct i2c_driver imx355_i2c_driver = {
        .driver = {
                .name = "imx355",
                .acpi_match_table = ACPI_PTR(imx355_acpi_ids),
+               .of_match_table = imx355_match_table,
+               .pm = &imx355_pm_ops,
        },
        .probe = imx355_probe,
        .remove = imx355_remove,

I think reset should be asserted before regulators and power are switched on. i.e. before you try to switch the chip on, you should establish that the reset pin is in the state that the timing diagram calls for.

If we look at imx214 which someone has posted on the internet

https://www.v-visiontech.com/web/userfiles/download/IMX214-0AQH5-C_2.0.0ExcellenceCommsen-281-29_mASEw.pdf

Pages 28 and 29

See timing value T4 - you need to provide power and clock for T4 before de-asserting reset and then wait for T7 before starting to stream.

We don't have the imx315 spec but likely imx355 has a similar start-up state machine.

1. Assert reset
2. Power up
3. Start clock
4. t4
5. De-assert reset
6. T6 - wait time to first i2c transaction
7. T7 - wait time to first stream on

You should definitely set the reset to logical on in power_on() as you don't necessarily know the state of the reset pin each time you power on.

---
bod

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