Re: [PATCH V8 2/2] media: i2c: dw9768: Add DW9768 VCM driver

[Dongchun Zhu <dongchun.zhu@mediatek.com>]

Hello Tomasz,

Thanks for the review.

On Thu, 2020-06-18 at 18:45 +0000, Tomasz Figa wrote:
> On Tue, Jun 16, 2020 at 08:55:31PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for DW9768 voice coil motor,
> > providing control to set the desired focus via IIC serial interface.
> > 
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > ---
> >  MAINTAINERS                |   1 +
> >  drivers/media/i2c/Kconfig  |  12 +
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9768.c | 553 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 567 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9768.c
> [snip]
> > +static int dw9768_probe(struct i2c_client *client)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct dw9768 *dw9768;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
> > +	if (!dw9768)
> > +		return -ENOMEM;
> > +
> > +	/* Initialize subdev */
> > +	v4l2_i2c_subdev_init(&dw9768->sd, client, &dw9768_ops);
> > +
> > +	dw9768->aac_mode = DW9768_AAC_MODE_DEFAULT;
> > +	dw9768->aac_timing = DW9768_AAC_TIME_DEFAULT;
> > +	dw9768->clock_presc = DW9768_CLOCK_PRE_SCALE_DEFAULT;
> > +
> > +	/* Optional indication of AAC mode select */
> > +	fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-mode",
> > +				 &dw9768->aac_mode);
> > +
> > +	/* Optional indication of clock pre-scale select */
> > +	fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,clock-presc",
> > +				 &dw9768->clock_presc);
> > +
> > +	/* Optional indication of AAC Timing */
> > +	fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-timing",
> > +				 &dw9768->aac_timing);
> > +
> > +	dw9768->move_delay_us = dw9768_cal_move_delay(dw9768->aac_mode,
> > +						      dw9768->clock_presc,
> > +						      dw9768->aac_timing) / 100;
> 
> nit: Could we make the function return the value in us already? One would
> expect the function to return the value in a standard unit, so this
> division by 100 here is confusing.
> 

Good idea.

> > +
> > +	for (i = 0; i < ARRAY_SIZE(dw9768_supply_names); i++)
> > +		dw9768->supplies[i].supply = dw9768_supply_names[i];
> > +
> > +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dw9768_supply_names),
> > +				      dw9768->supplies);
> > +	if (ret) {
> > +		dev_err(dev, "failed to get regulators\n");
> > +		return ret;
> > +	}
> > +
> > +	/* Initialize controls */
> > +	ret = dw9768_init_controls(dw9768);
> > +	if (ret)
> > +		goto err_free_handler;
> > +
> > +	/* Initialize subdev */
> > +	dw9768->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > +	dw9768->sd.internal_ops = &dw9768_int_ops;
> > +
> > +	ret = media_entity_pads_init(&dw9768->sd.entity, 0, NULL);
> > +	if (ret < 0)
> > +		goto err_free_handler;
> > +
> > +	dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
> > +
> > +	pm_runtime_enable(dev);
> > +	if (!pm_runtime_enabled(dev)) {
> > +		ret = dw9768_runtime_resume(dev);
> > +		if (ret < 0) {
> > +			dev_err(dev, "failed to power on: %d\n", ret);
> > +			goto err_clean_entity;
> > +		}
> > +	}
> > +
> > +	ret = v4l2_async_register_subdev(&dw9768->sd);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> > +		goto err_power_off;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_power_off:
> > +	pm_runtime_disable(dev);
> > +	if (!pm_runtime_enabled(dev))
> 
> We just disabled runtime PM in the line above, so this check would be
> always true. Need to call pm_runtime_disable() after this if.
> 

Sorry to make such a mistake.

> > +		dw9768_runtime_suspend(dev);
> > +err_clean_entity:
> > +	media_entity_cleanup(&dw9768->sd.entity);
> > +err_free_handler:
> > +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> > +
> > +	return ret;
> > +}
> > +
> > +static int dw9768_remove(struct i2c_client *client)
> > +{
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct dw9768 *dw9768 = sd_to_dw9768(sd);
> > +
> > +	v4l2_async_unregister_subdev(&dw9768->sd);
> > +	v4l2_ctrl_handler_free(&dw9768->ctrls);
> > +	media_entity_cleanup(&dw9768->sd.entity);
> > +	pm_runtime_disable(&client->dev);
> > +	if (!pm_runtime_suspended(&client->dev))
> 
> Oops, I just realized that my suggestion about the function to use here
> was incorrect. pm_runtime_status_suspended() should be the correct function
> here. Sorry for the confusion.
> 
> This is because we only have 2 cases here:
>  - runtime PM compiled out - the stubs function is used, which returns
>    false, so the condition is true,
>  - runtime PM compiled in - we enabled runtime PM in probe, so here we
>    don't need to consider the enable state.
> 

Uh-huh...
Thanks for the explaining.
It seems OV8856, OV5695 and OV2685 also use the API
'pm_runtime_status_suspended'.

> Best regards,
> Tomasz

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