Re: [PATCH v2] media: i2c: dw9714: add optional regulator support

Sakari Ailus
2021-11-26T10:48:13Z

Hi Martin,

On Fri, Nov 26, 2021 at 10:01:07AM +0100, Martin Kepplinger wrote:
> From: Angus Ainslie <angus@akkea.ca>
>
> Allow the dw9714 to control a regulator and adjust suspend() and resume()
> to support both runtime and system pm.
>
> Signed-off-by: Angus Ainslie <angus@akkea.ca>
> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> ---
>
> revision history
> ----------------
>
> v2: (thank you Mark)
> * simplify the regulator_get_optional() error path
> * fix regulator usage during probe()
>
> v1:
> https://lore.kernel.org/linux-media/20211125080922.978583-1-martin.kepplinger@puri.sm/
>
>
>
> drivers/media/i2c/dw9714.c | 39 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
> index 3863dfeb8293..e8cc19b89861 100644
> --- a/drivers/media/i2c/dw9714.c
> +++ b/drivers/media/i2c/dw9714.c
> @@ -5,6 +5,7 @@
> #include <linux/i2c.h>
> #include <linux/module.h>
> #include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
> #include <media/v4l2-ctrls.h>
> #include <media/v4l2-device.h>
> #include <media/v4l2-event.h>
> @@ -36,6 +37,7 @@ struct dw9714_device {
> struct v4l2_ctrl_handler ctrls_vcm;
> struct v4l2_subdev sd;
> u16 current_val;
> + struct regulator *vcc;
> };
>
> static inline struct dw9714_device *to_dw9714_vcm(struct v4l2_ctrl *ctrl)
> @@ -145,6 +147,21 @@ static int dw9714_probe(struct i2c_client *client)
> if (dw9714_dev == NULL)
> return -ENOMEM;
>
> + dw9714_dev->vcc = devm_regulator_get_optional(&client->dev, "vcc");

You you used regular devm_regulator_get(), you could remove the error
handling below. If there's no regulator, you'll simply get a dummy one.

> + if (IS_ERR(dw9714_dev->vcc)) {
> + dev_dbg(&client->dev, "No vcc regulator found: %ld\n",
> + PTR_ERR(dw9714_dev->vcc));
> + dw9714_dev->vcc = NULL;
> + }
> +
> + if (dw9714_dev->vcc) {

With (dummy) regulators, these checks become unnecessary.

> + rval = regulator_enable(dw9714_dev->vcc);
> + if (rval < 0) {
> + dev_err(&client->dev, "failed to enable vcc: %d\n", rval);
> + return rval;
> + }
> + }
> +
> v4l2_i2c_subdev_init(&dw9714_dev->sd, client, &dw9714_ops);
> dw9714_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
> V4L2_SUBDEV_FL_HAS_EVENTS;
> @@ -200,6 +217,9 @@ static int __maybe_unused dw9714_vcm_suspend(struct device *dev)
> struct dw9714_device *dw9714_dev = sd_to_dw9714_vcm(sd);
> int ret, val;
>
> + if (pm_runtime_suspended(&client->dev))
> + return 0;

This can't take place in a runtime PM suspend callback. You'll need to add
system suspend callback for this.

> +
> for (val = dw9714_dev->current_val & ~(DW9714_CTRL_STEPS - 1);
> val >= 0; val -= DW9714_CTRL_STEPS) {
> ret = dw9714_i2c_write(client,
> @@ -208,6 +228,13 @@ static int __maybe_unused dw9714_vcm_suspend(struct device *dev)
> dev_err_once(dev, "%s I2C failure: %d", __func__, ret);
> usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 10);
> }
> +
> + if (dw9714_dev->vcc) {
> + ret = regulator_disable(dw9714_dev->vcc);
> + if (ret)
> + dev_err(dev, "Failed to disable vcc: %d\n", ret);
> + }
> +
> return 0;
> }
>
> @@ -224,6 +251,18 @@ static int __maybe_unused dw9714_vcm_resume(struct device *dev)
> struct dw9714_device *dw9714_dev = sd_to_dw9714_vcm(sd);
> int ret, val;
>
> + if (pm_runtime_suspended(&client->dev))

Same for this one.

> + return 0;
> +
> + if (dw9714_dev->vcc) {
> + ret = regulator_enable(dw9714_dev->vcc);
> + if (ret) {
> + dev_err(dev, "Failed to enable vcc: %d\n", ret);
> + return ret;
> + }
> + usleep_range(1000, 2000);
> + }
> +
> for (val = dw9714_dev->current_val % DW9714_CTRL_STEPS;
> val < dw9714_dev->current_val + DW9714_CTRL_STEPS - 1;
> val += DW9714_CTRL_STEPS) {

--
Kind regards,

Sakari Ailus