Re: [PATCH v2 3/3] media: i2c: ak7375: Add regulator management

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On Mon, Jul 11 2022 at 19:31:23 +0200, Jacopo Mondi <jacopo@xxxxxxxxxx> wrote:
Hi Yassine,

On Mon, Jul 11, 2022 at 06:40:39PM +0400, Yassine Oudjana wrote:
 From: Yassine Oudjana <y.oudjana@xxxxxxxxxxxxxx>

 Make the driver get needed regulators on probe and enable/disable
 them on runtime PM callbacks.

 Signed-off-by: Yassine Oudjana <y.oudjana@xxxxxxxxxxxxxx>
 ---
 Changes since v1:
   - Reorganize variable declaration
   - Change the power-on delay range to 3000-3500 microseconds.

drivers/media/i2c/ak7375.c | 39 ++++++++++++++++++++++++++++++++++++++
  1 file changed, 39 insertions(+)

 diff --git a/drivers/media/i2c/ak7375.c b/drivers/media/i2c/ak7375.c
 index 40b1a4aa846c..c2b2542a0056 100644
 --- a/drivers/media/i2c/ak7375.c
 +++ b/drivers/media/i2c/ak7375.c
 @@ -6,6 +6,7 @@
  #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>

 @@ -23,17 +24,32 @@
   */
  #define AK7375_CTRL_STEPS	64
  #define AK7375_CTRL_DELAY_US	1000
 +/*
 + * The vcm takes around 3 ms to power on and start taking
 + * I2C messages. This value was found experimentally due to
 + * lack of documentation.
 + */
 +#define AK7375_POWER_DELAY_US	3000

  #define AK7375_REG_POSITION	0x0
  #define AK7375_REG_CONT		0x2
  #define AK7375_MODE_ACTIVE	0x0
  #define AK7375_MODE_STANDBY	0x40

 +static const char * const ak7375_supply_names[] = {
 +	"vdd",
 +	"vio",
 +};
 +
 +#define AK7375_NUM_SUPPLIES ARRAY_SIZE(ak7375_supply_names)
 +
  /* ak7375 device structure */
  struct ak7375_device {
  	struct v4l2_ctrl_handler ctrls_vcm;
  	struct v4l2_subdev sd;
  	struct v4l2_ctrl *focus;
 +	struct regulator_bulk_data supplies[AK7375_NUM_SUPPLIES];
 +
  	/* active or standby mode */
  	bool active;
  };
@@ -133,12 +149,24 @@ static int ak7375_probe(struct i2c_client *client)
  {
  	struct ak7375_device *ak7375_dev;
  	int ret;
 +	int i;

  	ak7375_dev = devm_kzalloc(&client->dev, sizeof(*ak7375_dev),
  				  GFP_KERNEL);
  	if (!ak7375_dev)
  		return -ENOMEM;

 +	for (i = 0; i < AK7375_NUM_SUPPLIES; i++)
 +		ak7375_dev->supplies[i].supply = ak7375_supply_names[i];
 +
 +	ret = devm_regulator_bulk_get(&client->dev, AK7375_NUM_SUPPLIES,
 +				      ak7375_dev->supplies);
 +	if (ret) {
 +		dev_err(&client->dev, "Failed to get regulators: %pe",
 +			ERR_PTR(ret));

Why are you using %pe here ? Your return value is not a pointer

In order to have it print a symbolic error name instead of a value
with CONFIG_SYMBOLIC_ERRNAME=y. There is no format code for an
error integer (or at least I couldn't find one mentioned anywhere
in the docs), so instead I use %pe then wrap `ret` in ERR_PTR().

(Also, missing \n at the end of the string)

That wasn't intentional. I'll fix it.


From Documentation/core-api/printk-formats.rst:
	%pe	-ENOSPC

For printing error pointers (i.e. a pointer for which IS_ERR() is true)
as a symbolic error name. Error values for which no symbolic name is
known are printed in decimal, while a non-ERR_PTR passed as the
argument to %pe gets treated as ordinary %p.

 +		return ret;
 +	}
 +
  	v4l2_i2c_subdev_init(&ak7375_dev->sd, client, &ak7375_ops);
  	ak7375_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
  	ak7375_dev->sd.internal_ops = &ak7375_int_ops;
@@ -210,6 +238,10 @@ static int __maybe_unused ak7375_vcm_suspend(struct device *dev)
  	if (ret)
  		dev_err(dev, "%s I2C failure: %d\n", __func__, ret);

+ ret = regulator_bulk_disable(AK7375_NUM_SUPPLIES, ak7375_dev->supplies);
 +	if (ret)
 +		return ret;
 +
  	ak7375_dev->active = false;

  	return 0;
@@ -230,6 +262,13 @@ static int __maybe_unused ak7375_vcm_resume(struct device *dev)
  	if (ak7375_dev->active)
  		return 0;

+ ret = regulator_bulk_enable(AK7375_NUM_SUPPLIES, ak7375_dev->supplies);
 +	if (ret)
 +		return ret;
 +
 +	/* Wait for vcm to become ready */
 +	usleep_range(AK7375_POWER_DELAY_US, AK7375_POWER_DELAY_US + 500);
 +
  	ret = ak7375_i2c_write(ak7375_dev, AK7375_REG_CONT,
  		AK7375_MODE_ACTIVE, 1);
  	if (ret) {
 --
 2.37.0






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