> +/** > + * wbrf_supported_producer - Determine if the device can report frequencies > + * > + * @dev: device pointer > + * > + * WBRF is used to mitigate devices that cause harmonic interference. > + * This function will determine if this device needs to report such frequencies. How is the WBRF core supposed to answer this question? That it knows there is at least one device which has registered with WBRF saying it can change its behaviour to avoid causing interference? Rather than "Determine if the device can report frequencies" should it be "Determine if the device should report frequencies" A WiFi device can always report frequencies, since it knows what frequency is it currently using. However, it is pointless making such reports if there is no device which can actually make use of the information. > +bool wbrf_supported_producer(struct device *dev) > +{ > + return true; > +} I found the default implementation of true being odd. It makes me wounder, what is the point of this call. I would expect this to see if a linked list is empty or not. > +/** > + * wbrf_supported_consumer - Determine if the device can react to frequencies This again seems odd. A device should know if it can react to frequencies or not. WBRF core should not need to tell it. What makes more sense to me is that this call is about a device telling the WBRF core it is able to react to frequencies. The WBRF core then can give a good answer to wbrf_supported_producer(), yes, i know of some other device who might be able to do something to avoid causing interference to you, so please do tell me about frequencies you want to use. What is missing here in this API is policy information. The WBRF core knows it has zero or more devices which can report what frequencies they are using, and it has zero or more devices which maybe can do something. But then you need policy to say this particular board needs any registered devices to actually do something because of poor shielding. Should this policy be as simple as a bool, or should it actually say the board has shielding issues for a list of frequencies? I think the answer to what will depend on the cost of taking action when no action is actually required. > + * wbrf_register_notifier - Register for notifications of frequency changes > + * > + * @nb: driver notifier block > + * > + * WBRF is used to mitigate devices that cause harmonic interference. > + * This function will allow consumers to register for frequency notifications. > + */ > +int wbrf_register_notifier(struct notifier_block *nb) > +{ > + return blocking_notifier_chain_register(&wbrf_chain_head, nb); > +} What are the timing requirements for the handler? Should the handler block until the device has finished doing what it needs to do and the frequency response has settled? We don't want the WiFi device doing a SNR measurement until we know local noise is at a minimum. I think it would be good to document things like this here. > +struct wbrf_ranges_out { > + u32 num_of_ranges; > + struct exclusion_range band_list[MAX_NUM_OF_WBRF_RANGES]; > +} __packed; Seems odd using packed here. It is the only structure which is packed. I would also move the u32 after the struct so it is naturally aligned on 64 bit systems. Andrew