Hello Shunqian, On Wed, Jan 10, 2018 at 10:06:05AM +0800, Shunqian Zheng wrote: [snip] > +static int __ov5695_start_stream(struct ov5695 *ov5695) > +{ > + int ret; > + > + ret = ov5695_write_array(ov5695->client, ov5695_global_regs); > + if (ret) > + return ret; > + ret = ov5695_write_array(ov5695->client, ov5695->cur_mode->reg_list); > + if (ret) > + return ret; > + > + /* In case these controls are set before streaming */ > + ret = __v4l2_ctrl_handler_setup(&ov5695->ctrl_handler); > + if (ret) > + return ret; > + > + return ov5695_write_reg(ov5695->client, OV5695_REG_CTRL_MODE, > + OV5695_REG_VALUE_08BIT, OV5695_MODE_STREAMING); > +} > + > +static int __ov5695_stop_stream(struct ov5695 *ov5695) > +{ > + return ov5695_write_reg(ov5695->client, OV5695_REG_CTRL_MODE, > + OV5695_REG_VALUE_08BIT, OV5695_MODE_SW_STANDBY); > +} > + > +static int ov5695_s_stream(struct v4l2_subdev *sd, int on) > +{ > + struct ov5695 *ov5695 = to_ov5695(sd); > + struct i2c_client *client = ov5695->client; > + int ret = 0; > + > + mutex_lock(&ov5695->mutex); > + on = !!on; > + if (on == ov5695->streaming) > + goto unlock_and_return; > + > + if (on) { > + ret = pm_runtime_get_sync(&client->dev); > + if (ret < 0) { > + pm_runtime_put_noidle(&client->dev); > + goto unlock_and_return; > + } > + > + ret = __ov5695_start_stream(ov5695); > + if (ret) { > + v4l2_err(sd, "start stream failed while write regs\n"); > + pm_runtime_put(&client->dev); > + goto unlock_and_return; > + } > + } else { > + __ov5695_stop_stream(ov5695); > + ret = pm_runtime_put(&client->dev); I would return the result of __ov5695_stop_stream() instead of pm_runtime_put(). I know I asked for this, but if the first s_stream(0) fails, the sensor may not have been stopped but the interface will be put in "streaming = 0" state, preventing a second s_stream(0) to be issued because of your check "on == ov5695->streaming" a few lines above. I can't tell how bad this is. Imho is acceptable but I would like to hear someone else opinion here :) > + } > + > + ov5695->streaming = on; > + > +unlock_and_return: > + mutex_unlock(&ov5695->mutex); > + > + return ret; > +} > + > + [snip] > +static const struct of_device_id ov5695_of_match[] = { > + { .compatible = "ovti,ov5695" }, > + {}, > +}; If you don't list CONFIG_OF as a dependecy for this driver (which you should not imho), please guard this with: #if IS_ENABLED(CONFIG_OF) #endif > + > +static struct i2c_driver ov5695_i2c_driver = { > + .driver = { > + .name = "ov5695", > + .owner = THIS_MODULE, > + .pm = &ov5695_pm_ops, > + .of_match_table = ov5695_of_match > + }, > + .probe = &ov5695_probe, > + .remove = &ov5695_remove, > +}; > + > +module_i2c_driver(ov5695_i2c_driver); > + > +MODULE_DESCRIPTION("OmniVision ov5695 sensor driver"); > +MODULE_LICENSE("GPL v2"); As you've fixed my comments on v1, and with the above bits addressed: Reviewed-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> Thanks j > -- > 1.9.1 >