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. -- Best regards, Bingbu Cao