Re: [PATCH v5 3/6] ov5670: Support probe whilst the device is in a low power state

Sakari Ailus
2020-08-12T09:22:23Z

Hi Bingbu,

Thanks for the review.

On Wed, Aug 12, 2020 at 05:12:28PM +0800, Bingbu Cao wrote:
>
>
> On 8/10/20 10:27 PM, Sakari Ailus wrote:
> > Tell ACPI device PM code that the driver supports the device being in a
> > low power state when the driver's probe function is entered.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> > drivers/media/i2c/ov5670.c | 23 ++++++++++++++---------
> > 1 file changed, 14 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5670.c b/drivers/media/i2c/ov5670.c
> > index f26252e35e08d..1f75b888d2a18 100644
> > --- a/drivers/media/i2c/ov5670.c
> > +++ b/drivers/media/i2c/ov5670.c
> > @@ -2456,6 +2456,7 @@ static int ov5670_probe(struct i2c_client *client)
> > struct ov5670 *ov5670;
> > const char *err_msg;
> > u32 input_clk = 0;
> > + bool low_power;
> > int ret;
> >
> > device_property_read_u32(&client->dev, "clock-frequency", &input_clk);
> > @@ -2472,11 +2473,14 @@ static int ov5670_probe(struct i2c_client *client)
> > /* Initialize subdev */
> > v4l2_i2c_subdev_init(&ov5670->sd, client, &ov5670_subdev_ops);
> >
> > - /* Check module identity */
> > - ret = ov5670_identify_module(ov5670);
> > - if (ret) {
> > - err_msg = "ov5670_identify_module() error";
> > - goto error_print;
> > + low_power = acpi_dev_state_low_power(&client->dev);
> > + if (!low_power) {
> > + /* Check module identity */
> > + ret = ov5670_identify_module(ov5670);
> > + if (ret) {
> > + err_msg = "ov5670_identify_module() error";
> > + goto error_print;
> > +
>
> Sakari, thanks for your patch.
> one question - With this change, there will be no chance for driver to guarantee
> that the camera sensor plugged in is the camera that the matched driver actually
> can drive until try to streaming the camera, so is it necessary to return
> appropriate error in .s_stream ops to notify user it is not the hardware that
> current driver can drive? if no other better way.

Indeed sensor identification is now skipped in probe. I'll add that for v6
--- and check other drivers, too.

--
Kind regards,

Sakari Ailus