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@xxxxxxxxxxxxxxx> > > --- > > 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