Re: [PATCH 1/2] nl80211: vendor-cmd: qca: add dynamic SAR power limits

[Pkshih <pkshih@realtek.com>]

On Wed, 2019-12-18 at 17:48 +0200, Kalle Valo wrote:
> From: Wen Gong <wgong@codeaurora.org>
> 
> The vendor commands is to add API for user to configure dynamic SAR
> power limits, it will not replace the existing power control
> functionality, it is to make more convenient to configure power.
> 
> An example of usage(wlan0 is the wireless interface dev name):
> iw dev wlan0 vendor send 0x1374 0x92 0x2C 0x00 0x03 0x00 0x14 0x00 0x01
> 0x00 0x08 0x00 0x07 0x00 0x22 0x00 0x00 0x00 0x08 0x00 0x04 0x00 0x00
> 0x00 0x00 0x00 0x14 0x00 0x02 0x00 0x08 0x00 0x07 0x00 0x11 0x00 0x00
> 0x00 0x08 0x00 0x04 0x00 0x01 0x00 0x00 0x00
> 
> means of bytes:
> 0x1374: vendor id
> 0x92: vendor subcmd id
> 0x22: 2.4G power limit
> 0x11: 5G power limit
> 
> Tested with QCA6174 SDIO with firmware WLAN.RMH.4.4.1-00029.
> 
> Signed-off-by: Wen Gong <wgong@codeaurora.org>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
> ---
>  include/uapi/nl80211-vnd-qca.h | 68
> ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
>  create mode 100644 include/uapi/nl80211-vnd-qca.h
> 
> diff --git a/include/uapi/nl80211-vnd-qca.h b/include/uapi/nl80211-vnd-qca.h
> new file mode 100644
> index 000000000000..482c9409a2c0
> --- /dev/null
> +++ b/include/uapi/nl80211-vnd-qca.h
> @@ -0,0 +1,68 @@
> +/* SPDX-License-Identifier: ISC */
> +/*
> + * Copyright (c) 2019 The Linux Foundation. All rights reserved.
> + */
> +
> +#ifndef _UAPI_NL80211_VND_QCA_H
> +#define _UAPI_NL80211_VND_QCA_H
> +
> +/* Vendor id to be used in vendor specific command and events to user space
> + * NOTE: The authoritative place for definition of QCA_NL80211_VENDOR_ID,
> + * vendor subcmd definitions prefixed with QCA_NL80211_VENDOR_SUBCMD, and
> + * qca_wlan_vendor_attr is open source file src/common/qca-vendor.h in
> + * git://w1.fi/srv/git/hostap.git; the values here are just a copy of that
> + */
> +#define QCA_NL80211_VENDOR_ID 0x001374
> +
> +/**
> + * enum qca_nl80211_vendor_subcmds - QCA nl80211 vendor command identifiers
> + *
> + *@QCA_NL80211_VENDOR_SUBCMD_SET_SAR_LIMITS and is used to retrieve the
> + *	settings currently in use. The attributes returned by this command
> are
> + *	defined by enum qca_vendor_attr_sar_limits.
> + */
> +enum qca_nl80211_vendor_subcmds {
> +	QCA_NL80211_VENDOR_SUBCMD_SET_SAR_LIMITS = 146,
> +	};
> +
> +/**
> + * enum qca_vendor_attr_sar_limits - Attributes for SAR power limits
> + *
> + * @QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC: Nested array of SAR power
> + *	limit specifications. The number of specifications is
> + *	specified by @QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_NUM_SPECS. Each
> + *	specification contains a set of
> + *	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_* attributes. A
> + *	specification is uniquely identified by the attributes
> + *	%QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_BAND and always
> + *	contains as a payload the attribute
> + *	%QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_POWER_LIMIT.
> + *
> + * @QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_BAND: Optional (u32) value to
> + *	indicate for which band this specification applies. Valid
> + *	values are enumerated in enum %nl80211_band (although not all
> + *	bands may be supported by a given device). If the attribute is

Can we define separated enum to address four 5G sub-bands, likes

enum nl80211_sar_band {
	NL80211_SAR_BAND_2G,
	NL80211_SAR_BAND_5G_BAND1,
	NL80211_SAR_BAND_5G_BAND2,
	NL80211_SAR_BAND_5G_BAND3,
	NL80211_SAR_BAND_5G_BAND4,
};

I think this vendor command can be a generic nl80211 command, because
we need SAR
power limit as well.

> + *	not supplied then the specification will be applied to all
> + *	supported bands.
> + *
> + * @QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_POWER_LIMIT: Required (u32)
> + *	value to specify the actual power limit value in units of 0.5
> + *	dBm (i.e., a value of 11 represents 5.5 dBm).

Can we have higher precision, in unit of 0.125?


> + *	This is required, when %QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SELECT is
> + *	%QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SELECT_USER.
> + *
> + * These attributes are used with %QCA_NL80211_VENDOR_SUBCMD_SET_SAR_LIMITS
> + * and %QCA_NL80211_VENDOR_SUBCMD_GET_SAR_LIMITS.
> + */
> +enum qca_vendor_attr_sar_limits {
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_INVALID = 0,
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC = 3,
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_BAND = 4,
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SPEC_POWER_LIMIT = 7,

Why these enum aren't continual?
The reason may be because QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_SELECT and something
me
ntioned in above paragraph but missing in this enum?

They will waste memory when doing nla_parse() with tb[MAX];

> +
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_AFTER_LAST,
> +	QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_MAX =
> +		QCA_WLAN_VENDOR_ATTR_SAR_LIMITS_AFTER_LAST - 1
> +};
> +
> +#endif /* _UAPI_NL80211_VND_QCA_H_ */