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SubjectRe: [PATCH v8 3/3] iio: adc: add support for Allwinner SoCs ADC
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Hi Maxime,

On 10/12/2016 10:44, Maxime Ripard wrote:
> Hi,
>
> Just some minor comments.
>
> On Fri, Dec 09, 2016 at 11:22:36AM +0100, Quentin Schulz wrote:
>> + /*
>> + * Since the thermal sensor needs the IP to be in touchscreen mode and
>> + * there is no register to know if the IP has finished its transition
>> + * between the two modes, a delay is required when switching modes. This
>> + * slows down ADC readings while the latter are critical data to the
>
> The latter between what and what?
>
>> + * user. Disabling CONFIG_THERMAL_OF in kernel configuration allows the
>> + * user to avoid registering the thermal sensor (thus unavailable) and
>
> Isn't it obvious that it's not going to be available if you do not
> register it?
>
>> + * does not switch between modes thus "quicken" the ADC readings.
>> + * The thermal sensor should be enabled by default since the SoC
>> + * temperature is usually more critical than ADC readings.
>
> This last sentence should be in the Kconfig help. You cannot expect
> that all your users will read all the source code they want to compile
> :)
>
> Overall, I think this comment is kind of missing the point, maybe
> something like:
>
> /*
> * Since the controller needs to be in touchscreen mode for its
> * thermal sensor to operate properly, and that switching between the
> * two modes needs a delay, always registering in the thermal
> * framework will significantly slow down the conversion rate of the
> * ADCs.
> *
> * Therefore, instead of depending on THERMAL_OF in Kconfig, we only
> * register the sensor if that option is enabled, eventually leaving
> * that choice to the user.
> */
>
> Would be much clearer.
>
>> + */
>> +
>> + if (IS_ENABLED(CONFIG_THERMAL_OF)) {
>> + /*
>> + * This driver is a child of an MFD which has a node in the DT but not
>> + * its children. Therefore, the resulting devices of this driver do not
>
> Wrong indentation for the comment, and saying why the MFD children
> don't have a node in the DT (backward compatibility) would be nice.
>

Thanks for the comments, that's indeed much clearer.

>> + * have an of_node variable.
>> + * However, its parent (the MFD driver) has an of_node variable and
>> + * since devm_thermal_zone_of_sensor_register uses its first argument to
>> + * match the phandle defined in the node of the thermal driver with the
>> + * of_node of the device passed as first argument and the third argument
>> + * to call ops from thermal_zone_of_device_ops, the solution is to use
>> + * the parent device as first argument to match the phandle with its
>> + * of_node, and the device from this driver as third argument to return
>> + * the temperature.
>> + */
>> + tzd = devm_thermal_zone_of_sensor_register(pdev->dev.parent, 0,
>> + info,
>> + &sun4i_ts_tz_ops);
>
> I don't think tzd is used anywhere else in your function, it can be
> made local to this block.
>

ACK.

Thanks,
Quentin

--
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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