Re: [PATCH v3 8/9] media: i2c: ov08d10: add support for reset and power management

[Matthias Fend <matthias.fend.oss@emfend.at>]

Hi Sakari,

Am 26.03.2026 um 14:26 schrieb Sakari Ailus:
> Hi Matthias,
> 
> A few more minor comments.
> 
> On Tue, Mar 24, 2026 at 11:41:42AM +0100, Matthias Fend wrote:
>> Add support for the required power supplies as well as the control of an
>> optional sensor reset.
>>
>> Signed-off-by: Matthias Fend <matthias.fend@emfend.at>
>> ---
>>   drivers/media/i2c/ov08d10.c | 93 ++++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 92 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/i2c/ov08d10.c b/drivers/media/i2c/ov08d10.c
>> index ce0fa30a86129302b5dda0b8796e44054fd77c88..19035991e8bb164d4fca5d87ee4551191974e8bb 100644
>> --- a/drivers/media/i2c/ov08d10.c
>> +++ b/drivers/media/i2c/ov08d10.c
>> @@ -8,6 +8,7 @@
>>   #include <linux/module.h>
>>   #include <linux/pm_runtime.h>
>>   #include <linux/regulator/consumer.h>
>> +#include <linux/reset.h>
>>   #include <media/v4l2-ctrls.h>
>>   #include <media/v4l2-device.h>
>>   #include <media/v4l2-fwnode.h>
>> @@ -513,9 +514,17 @@ static const char * const ov08d10_test_pattern_menu[] = {
>>   	"Standard Color Bar",
>>   };
>>   
>> +static const char *const ov08d10_supply_names[] = {
>> +	"dovdd",	/* Digital I/O power */
>> +	"avdd",		/* Analog power */
>> +	"dvdd",		/* Digital core power */
>> +};
>> +
>>   struct ov08d10 {
>>   	struct device *dev;
>>   	struct clk *clk;
>> +	struct reset_control *reset;
>> +	struct regulator_bulk_data supplies[ARRAY_SIZE(ov08d10_supply_names)];
>>   
>>   	struct v4l2_subdev sd;
>>   	struct media_pad pad;
>> @@ -1265,6 +1274,56 @@ static const struct v4l2_subdev_internal_ops ov08d10_internal_ops = {
>>   	.open = ov08d10_open,
>>   };
>>   
>> +static int ov08d10_power_off(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct ov08d10 *ov08d10 = to_ov08d10(sd);
>> +
>> +	reset_control_assert(ov08d10->reset);
>> +
>> +	regulator_bulk_disable(ARRAY_SIZE(ov08d10->supplies),
>> +			       ov08d10->supplies);
>> +
>> +	clk_disable_unprepare(ov08d10->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ov08d10_power_on(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct ov08d10 *ov08d10 = to_ov08d10(sd);
>> +	int ret;
>> +
>> +	ret = regulator_bulk_enable(ARRAY_SIZE(ov08d10->supplies),
>> +				    ov08d10->supplies);
>> +	if (ret < 0) {
>> +		dev_err(dev, "failed to enable regulators: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = clk_prepare_enable(ov08d10->clk);
>> +	if (ret < 0) {
>> +		regulator_bulk_disable(ARRAY_SIZE(ov08d10->supplies),
>> +				       ov08d10->supplies);
>> +
>> +		dev_err(dev, "failed to enable imaging clock: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	if (ov08d10->reset) {
>> +		/* Delay from DVDD stable to sensor XSHUTDN pull up: 5ms */
>> +		fsleep(5 * USEC_PER_MSEC);
>> +
>> +		reset_control_deassert(ov08d10->reset);
>> +
>> +		/* Delay from XSHUTDN pull up to SCCB start: 8ms */
>> +		fsleep(8 * USEC_PER_MSEC);
> 
> Don't you need the fsleep()'s (or at least the latter one) even if you have
> no reset GPIO?

Good point. I couldn't find any explicit information in the datasheet 
about operating without a hardware reset.

While I didn't encounter any problems during my tests without a reset, 
that's probably just coincidence, and I think it's a good idea to wait 
for the delay you suggested in any case.

> 
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   static int ov08d10_identify_module(struct ov08d10 *ov08d10)
>>   {
>>   	struct i2c_client *client = v4l2_get_subdevdata(&ov08d10->sd);
>> @@ -1371,6 +1430,10 @@ static void ov08d10_remove(struct i2c_client *client)
>>   	media_entity_cleanup(&sd->entity);
>>   	v4l2_ctrl_handler_free(sd->ctrl_handler);
>>   	pm_runtime_disable(ov08d10->dev);
>> +	if (!pm_runtime_status_suspended(ov08d10->dev)) {
>> +		ov08d10_power_off(ov08d10->dev);
>> +		pm_runtime_set_suspended(ov08d10->dev);
>> +	}
>>   	mutex_destroy(&ov08d10->mutex);
>>   }
>>   
>> @@ -1378,6 +1441,7 @@ static int ov08d10_probe(struct i2c_client *client)
>>   {
>>   	struct ov08d10 *ov08d10;
>>   	unsigned long freq;
>> +	unsigned int i;
>>   	int ret;
>>   
>>   	ov08d10 = devm_kzalloc(&client->dev, sizeof(*ov08d10), GFP_KERNEL);
>> @@ -1403,12 +1467,32 @@ static int ov08d10_probe(struct i2c_client *client)
>>   		return ret;
>>   	}
>>   
>> +	ov08d10->reset = devm_reset_control_get_optional_exclusive(ov08d10->dev, NULL);
> 
> This is a bit long.
> 
> I'll take the set now but please post a fix on top.

I just posted a fixup. I hope it was as you intended.

Thanks
  ~Matthias

> 
>> +	if (IS_ERR(ov08d10->reset))
>> +		return dev_err_probe(ov08d10->dev, PTR_ERR(ov08d10->reset),
>> +				     "failed to get reset\n");
>> +	reset_control_assert(ov08d10->reset);
>> +
>> +	for (i = 0; i < ARRAY_SIZE(ov08d10_supply_names); i++)
>> +		ov08d10->supplies[i].supply = ov08d10_supply_names[i];
>> +
>> +	ret = devm_regulator_bulk_get(ov08d10->dev,
>> +				      ARRAY_SIZE(ov08d10->supplies),
>> +				      ov08d10->supplies);
>> +	if (ret)
>> +		return dev_err_probe(ov08d10->dev, ret,
>> +				     "failed to get regulators\n");
>> +
>>   	v4l2_i2c_subdev_init(&ov08d10->sd, client, &ov08d10_subdev_ops);
>>   
>> +	ret = ov08d10_power_on(ov08d10->dev);
>> +	if (ret)
>> +		return dev_err_probe(ov08d10->dev, ret, "failed to power on\n");
>> +
>>   	ret = ov08d10_identify_module(ov08d10);
>>   	if (ret) {
>>   		dev_err(ov08d10->dev, "failed to find sensor: %d\n", ret);
>> -		return ret;
>> +		goto probe_error_power_off;
>>   	}
>>   
>>   	mutex_init(&ov08d10->mutex);
>> @@ -1452,9 +1536,15 @@ static int ov08d10_probe(struct i2c_client *client)
>>   	v4l2_ctrl_handler_free(ov08d10->sd.ctrl_handler);
>>   	mutex_destroy(&ov08d10->mutex);
>>   
>> +probe_error_power_off:
>> +	ov08d10_power_off(ov08d10->dev);
>> +
>>   	return ret;
>>   }
>>   
>> +static DEFINE_RUNTIME_DEV_PM_OPS(ov08d10_pm_ops,
>> +				 ov08d10_power_off, ov08d10_power_on, NULL);
>> +
>>   #ifdef CONFIG_ACPI
>>   static const struct acpi_device_id ov08d10_acpi_ids[] = {
>>   	{ "OVTI08D1" },
>> @@ -1473,6 +1563,7 @@ MODULE_DEVICE_TABLE(of, ov08d10_of_match);
>>   static struct i2c_driver ov08d10_i2c_driver = {
>>   	.driver = {
>>   		.name = "ov08d10",
>> +		.pm = pm_ptr(&ov08d10_pm_ops),
>>   		.acpi_match_table = ACPI_PTR(ov08d10_acpi_ids),
>>   		.of_match_table = ov08d10_of_match,
>>   	},
>>
>