Re: [PATCH 1/2] media: ov2740: Add support for reset GPIO

[Hans de Goede <hdegoede@redhat.com>]

Hi Bingbu,

Thank you for the review!

On 11/20/23 05:04, Bingbu Cao wrote:
> 
> Hans,
> 
> Thanks for your patch.
> 
> On 11/15/23 8:38 PM, Hans de Goede wrote:
>> On some ACPI platforms, such as Chromebooks the ACPI methods to
>> change the power-state (_PS0 and _PS3) fully take care of powering
>> on/off the sensor.
>>
>> On other ACPI platforms, such as e.g. various ThinkPad models with
>> IPU6 + ov2740 sensor, the sensor driver must control the reset GPIO
>> and the sensor's clock itself.
>>
>> Add support for having the driver control an optional reset GPIO.
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>  drivers/media/i2c/ov2740.c | 48 ++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 46 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
>> index 24e468485fbf..e5f9569a229d 100644
>> --- a/drivers/media/i2c/ov2740.c
>> +++ b/drivers/media/i2c/ov2740.c
>> @@ -4,6 +4,7 @@
>>  #include <asm/unaligned.h>
>>  #include <linux/acpi.h>
>>  #include <linux/delay.h>
>> +#include <linux/gpio/consumer.h>
>>  #include <linux/i2c.h>
>>  #include <linux/module.h>
>>  #include <linux/pm_runtime.h>
>> @@ -333,6 +334,9 @@ struct ov2740 {
>>  	struct v4l2_ctrl *hblank;
>>  	struct v4l2_ctrl *exposure;
>>  
>> +	/* GPIOs, clocks */
> 
> It looks like the 'clock' should be in another one (2/2), :).

This was intentional to avoid churn in the form of
immediately changing the comment in the second patch :)

>> +	struct gpio_desc *reset_gpio;
>> +
>>  	/* Current mode */
>>  	const struct ov2740_mode *cur_mode;
>>  
>> @@ -1058,6 +1062,26 @@ static int ov2740_register_nvmem(struct i2c_client *client,
>>  	return 0;
>>  }
>>  
>> +static int ov2740_suspend(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct ov2740 *ov2740 = to_ov2740(sd);
>> +
>> +	gpiod_set_value_cansleep(ov2740->reset_gpio, 1);
>> +	return 0;
>> +}
>> +
>> +static int ov2740_resume(struct device *dev)
>> +{
>> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
>> +	struct ov2740 *ov2740 = to_ov2740(sd);
>> +
>> +	gpiod_set_value_cansleep(ov2740->reset_gpio, 0);
>> +	msleep(20);
> 
> I remember that usleep_range() is prefered for <=20ms.

I think that only applies to msleep <= 10ms, at least
check-patch is happy with this and I know it complains
about too short msleep() calls.

Regards,

Hans