6GHz channels are divided into preferred scanning channels(PSC)
and non-PSC channels. One in every four 20MHz channels is a PSC.
Spec mandates to use only PSC channels as primary channels for
setting up BSS on 6GHz only AP.
The set of 20 MHz channels in the 6 GHz band, with channel center
frequency, ch_a = Channel starting frequency – 55 + 80 × n (MHz)
are referred to as preferred scanning channels (PSCs) where,
n = 1, …, 15 as per IEEE P802.11ax/D6.1.
This function can be used by drivers or cfg80211 when making
scanning decision on 6GHz channels.
Signed-off-by: Pradeep Kumar Chitrapu <[email protected]>
---
v3:
- update channel starting frequency from 5945 to 5950 as per
IEEE P802.11ax/D6.1
- Define helper function and remove cahnnel flag PSC
include/net/cfg80211.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index fd6a973b1249..bd27020ea8c9 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -5281,6 +5281,30 @@ ieee80211_get_channel(struct wiphy *wiphy, int freq)
return ieee80211_get_channel_khz(wiphy, MHZ_TO_KHZ(freq));
}
+/**
+ * ieee80211_is_channel_psc - is 6ghz channel a Preferred Scanning Channel (PSC)
+ *
+ * @chan: struct ieee80211_channel to determine
+ * Return: True if 6ghz channel is a PSC channel. False for the rest.
+ */
+static inline bool ieee80211_is_channel_psc(struct ieee80211_channel *chan)
+{
+ if (chan->band != NL80211_BAND_6GHZ)
+ return false;
+
+ /*
+ * From IEEE P802.11ax/D6.1: The set of 20 MHz channels in the 6 GHz
+ * band, with channel center frequency, ch_a = Channel starting
+ * frequency – 55 80 × n (MHz) are referred to as preferred scanning
+ * channels (PSCs). Channel starting frequency is defined in 27.3.23.2
+ * (Channel allocation in the 6 GHz band), and n = 1, …, 15.
+ */
+ if (!(((chan->center_freq - 5950 + 55) >> 4) % 5))
+ return true;
+
+ return false;
+}
+
/**
* ieee80211_get_response_rate - get basic rate for a given rate
*
--
2.17.1
On Tue, 2020-05-26 at 15:42 -0700, Pradeep Kumar Chitrapu wrote:
Hi,
Just checked what we had here, and it was the following:
> +/**
> + * ieee80211_is_channel_psc - is 6ghz channel a Preferred Scanning Channel (PSC)
> + *
> + * @chan: struct ieee80211_channel to determine
> + * Return: True if 6ghz channel is a PSC channel. False for the rest.
> + */
> +static inline bool ieee80211_is_channel_psc(struct ieee80211_channel *chan)
> +{
> + if (chan->band != NL80211_BAND_6GHZ)
> + return false;
> +
> + /*
> + * From IEEE P802.11ax/D6.1: The set of 20 MHz channels in the 6 GHz
> + * band, with channel center frequency, ch_a = Channel starting
> + * frequency – 55 80 × n (MHz) are referred to as preferred scanning
> + * channels (PSCs). Channel starting frequency is defined in 27.3.23.2
> + * (Channel allocation in the 6 GHz band), and n = 1, …, 15.
> + */
> + if (!(((chan->center_freq - 5950 + 55) >> 4) % 5))
> + return true;
> +
> + return false;
> +}
static inline bool cfg80211_is_psc(struct ieee80211_channel *chan)
{
int chan_num =
ieee80211_frequency_to_channel(chan->center_freq);
return chan->band == NL80211_BAND_6GHZ && chan_num % 16 == 5;
}
Apart from the naming, where I guess I prefer actually
cfg80211_channel_is_psc()
or so, does that seem reasonable to you? I'd prefer not to hardcode
frequencies everywhere, so in that regard I like our version better.
Maybe bail out earlier if band != 6 ghz:
static inline bool cfg80211_channel_is_psc(struct ieee80211_channel *chan)
{
if (chan->band != NL80211_BAND_6GHZ)
return false;
return ieee80211_frequency_to_channel(chan->center_freq) % 16 == 5;
}
johannes
> static inline bool cfg80211_channel_is_psc(struct ieee80211_channel
> *chan)
> {
> if (chan->band != NL80211_BAND_6GHZ)
> return false;
>
> return ieee80211_frequency_to_channel(chan->center_freq) % 16 == 5;
> }
>
> johannes
sure Johannes. Above looks neat.
Thanks
pradeep