Re: [PATCH v3 1/4] dt-bindings: net: wireless: mt76: add power-limits node

[Rob Herring <robh@kernel.org>]

On Wed, Jul 15, 2020 at 03:01:34PM +0200, Felix Fietkau wrote:
> This subnode can be used to set per-rate tx power limits either per
> country code / regdomain or globally.
> These limits are typically provided by the device manufacturers and are
> used to limit sideband emissions and stay within regulatory limits
> 
> Co-developed-by: Shayne Chen <shayne.chen@mediatek.com>
> Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
> v3:
>  - fix S-o-b order
> v2:
>  - merge 802.11ax rate changes from Shayne's patch
>  - document txs-delta property

This is an extensive enough change that I think it needs to be in schema 
format.

>  .../bindings/net/wireless/mediatek,mt76.txt   | 59 +++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt b/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt
> index ab7e7a00e534..e4859c974ef4 100644
> --- a/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt
> +++ b/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt
> @@ -36,6 +36,7 @@ Optional nodes:
>  - led: Properties for a connected LED
>    Optional properties:
>      - led-sources: See Documentation/devicetree/bindings/leds/common.txt
> +- power-limits: contains per-regdomain/channel rate power limit subnodes
>  
>  &pcie {
>  	pcie0 {
> @@ -76,3 +77,61 @@ wmac: wmac@18000000 {
>  
>  	power-domains = <&scpsys MT7622_POWER_DOMAIN_WB>;
>  };
> +
> +
> +Subnodes of power-limits:
> +
> +Properties:
> +- country: One or more country codes, as used by the cfg80211 regdomain code

What are the values? cfg80211 is a Linux thing and doesn't belong in 
bindings.

> +- regdomain: "FCC", "ETSI" or "JP"

These aren't implied by the country code?

> +
> +If neither country, nor regdomain is specified, the power limits node is used
> +as a fallback when no other subnode matches.
> +
> +Subnodes txpower-2g, txpower-5g:
> +
> +Properties:
> +- channels: pairs of first and last channel number

What's the range in terms of channel numbers and pairs?

> +- cck: 4 half-dBm per-rate power limit values
> +- ofdm: 8 half-dBm per-rate power limit values
> +- mcs:
> +	sets of per-rate power limit values for 802.11n/802.11ac rates for
> +	multiple channel bandwidth settings.
> +	Each set starts with the number of channel bandwidth settings for
> +	which the rate set applies, followed by either 8 (MT7603/MT7628) or
> +	10 (all other chips) power limit values.
> +	The order of the channel bandwidth settings is: 20, 40, 80, 160 MHz.

The example only has 2 sets, so which channels are they?

> +- ru:
> +	sets of per-rate power limit values for 802.11ax rates for multiple
> +	channel bandwidth or resource unit settings.
> +	Each set starts with the number of channel bandwidth or resource unit
> +	settings for which the rate set applies, followed by 12 power limit
> +	values. The order of the channel resource unit settings is:
> +	RU26, RU52, RU106, RU242/SU20, RU484/SU40, RU996/SU80, RU2x996/SU160.

Could be 8-bit? Doesn't really matter much for the example, but what's 
the worst/typical case?

> +- txs-delta: half-dBm power delta for different numbers of antennas (1, 2, ...)
> +
> +
> +power-limit example:
> +
> +power-limits {
> +	r0 {

What's 'r0'? Not documented.

> +		regdomain = "FCC";
> +		txpower-5g {
> +			r1 {

What's 'r1' and 'r2'? Not documented.

> +				channels = <36 48>;
> +				ofdm = <23 23 23 23 23 23 23 23>;
> +				mcs = <1 23 23 23 23 23 23 23 23 23 23>,
> +					  <3 22 22 22 22 22 22 22 22 22 22>;
> +				ru = <3 22 22 22 22 22 22 22 22 22 22 22 22>,
> +				     <4 20 20 20 20 20 20 20 20 20 20 20 20>;
> +			};
> +			r2 {
> +				channels = <100 181>;
> +				ofdm = <14 14 14 14 14 14 14 14>;
> +				mcs = <4 14 14 14 14 14 14 14 14 14 14>;
> +				txs-delta = <12 9 6>;
> +				ru = <7 14 14 14 14 14 14 14 14 14 14 14 14>;
> +			};
> +		};
> +	};
> +};
> -- 
> 2.24.0
>