Re: [PATCH v2 03/22] cfg80211: regulatory: handle S1G channels

Thomas Pedersen
2020-09-05T18:38:50Z

On 2020-08-31 13:55, Thomas Pedersen wrote:
> S1G channels have a minimum bandwidth of 1Mhz, and there
> is a 1:1 mapping of allowed bandwidth to channel number.
>
> Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
>
> ---
>
> v2:
> - drop the freq_reg_info() interface changes and move the
> check for S1G band inside. Fixes a driver compile
> error.
> - fix iterating past bws[] in __freq_reg_info() by
> setting initial element to 0.
> Reported-by: kernel test robot <lkp@intel.com>
> ---
> net/wireless/reg.c | 70 ++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 58 insertions(+), 12 deletions(-)
>
> diff --git a/net/wireless/reg.c b/net/wireless/reg.c
> index 0ab7808fcec8..be6f54b70ad3 100644
> --- a/net/wireless/reg.c
> +++ b/net/wireless/reg.c
> @@ -1617,9 +1617,11 @@ __freq_reg_info(struct wiphy *wiphy, u32
> center_freq, u32 min_bw)
> {
> const struct ieee80211_regdomain *regd = reg_get_regdomain(wiphy);
> const struct ieee80211_reg_rule *reg_rule = NULL;
> + const u32 bws[] = {0, 1, 2, 4, 5, 8, 10, 16, 20};
> + int i = sizeof(bws) / sizeof(u32) - 1;

This could be 'int i = ARRAY_SIZE(bws) - 1'.

> u32 bw;
>
> - for (bw = MHZ_TO_KHZ(20); bw >= min_bw; bw = bw / 2) {
> + for (bw = MHZ_TO_KHZ(bws[i]); bw >= min_bw; bw =
> MHZ_TO_KHZ(bws[i--])) {
> reg_rule = freq_reg_info_regd(center_freq, regd, bw);
> if (!IS_ERR(reg_rule))
> return reg_rule;
> @@ -1631,7 +1633,9 @@ __freq_reg_info(struct wiphy *wiphy, u32
> center_freq, u32 min_bw)
> const struct ieee80211_reg_rule *freq_reg_info(struct wiphy *wiphy,
> u32 center_freq)
> {
> - return __freq_reg_info(wiphy, center_freq, MHZ_TO_KHZ(20));
> + u32 min_bw = center_freq < MHZ_TO_KHZ(1000) ? 1 : 20;
> +
> + return __freq_reg_info(wiphy, center_freq, MHZ_TO_KHZ(min_bw));
> }
> EXPORT_SYMBOL(freq_reg_info);
>
> @@ -1659,6 +1663,7 @@ static uint32_t reg_rule_to_chan_bw_flags(const
> struct ieee80211_regdomain *regd
> {
> const struct ieee80211_freq_range *freq_range = NULL;
> u32 max_bandwidth_khz, center_freq_khz, bw_flags = 0;
> + bool is_s1g = chan->band == NL80211_BAND_S1GHZ;
>
> freq_range = &reg_rule->freq_range;
>
> @@ -1678,16 +1683,57 @@ static uint32_t
> reg_rule_to_chan_bw_flags(const struct ieee80211_regdomain *regd
> MHZ_TO_KHZ(20)))
> bw_flags |= IEEE80211_CHAN_NO_20MHZ;
>
> - if (max_bandwidth_khz < MHZ_TO_KHZ(10))
> - bw_flags |= IEEE80211_CHAN_NO_10MHZ;
> - if (max_bandwidth_khz < MHZ_TO_KHZ(20))
> - bw_flags |= IEEE80211_CHAN_NO_20MHZ;
> - if (max_bandwidth_khz < MHZ_TO_KHZ(40))
> - bw_flags |= IEEE80211_CHAN_NO_HT40;
> - if (max_bandwidth_khz < MHZ_TO_KHZ(80))
> - bw_flags |= IEEE80211_CHAN_NO_80MHZ;
> - if (max_bandwidth_khz < MHZ_TO_KHZ(160))
> - bw_flags |= IEEE80211_CHAN_NO_160MHZ;
> + if (is_s1g) {
> + /* S1G is strict about non overlapping channels. We can
> + * calculate which bandwidth is allowed per channel by finding
> + * the largest bandwidth which cleanly divides the freq_range.
> + */
> + int edge_offset;
> + int ch_bw = max_bandwidth_khz;
> +
> + while (ch_bw) {
> + edge_offset = (center_freq_khz - ch_bw / 2) -
> + freq_range->start_freq_khz;
> + if (edge_offset % ch_bw == 0) {
> + switch (KHZ_TO_MHZ(ch_bw)) {
> + case 1:
> + bw_flags |= IEEE80211_CHAN_1MHZ;
> + break;
> + case 2:
> + bw_flags |= IEEE80211_CHAN_2MHZ;
> + break;
> + case 4:
> + bw_flags |= IEEE80211_CHAN_4MHZ;
> + break;
> + case 8:
> + bw_flags |= IEEE80211_CHAN_8MHZ;
> + break;
> + case 16:
> + bw_flags |= IEEE80211_CHAN_16MHZ;
> + break;
> + default:
> + /* If we got here, no bandwidths fit on
> + * this frequency, ie. band edge.
> + */
> + bw_flags |= IEEE80211_CHAN_DISABLED;
> + break;
> + }
> + break;
> + }
> + ch_bw /= 2;
> + }
> + } else {
> + if (max_bandwidth_khz < MHZ_TO_KHZ(10))
> + bw_flags |= IEEE80211_CHAN_NO_10MHZ;
> + if (max_bandwidth_khz < MHZ_TO_KHZ(20))
> + bw_flags |= IEEE80211_CHAN_NO_20MHZ;
> + if (max_bandwidth_khz < MHZ_TO_KHZ(40))
> + bw_flags |= IEEE80211_CHAN_NO_HT40;
> + if (max_bandwidth_khz < MHZ_TO_KHZ(80))
> + bw_flags |= IEEE80211_CHAN_NO_80MHZ;
> + if (max_bandwidth_khz < MHZ_TO_KHZ(160))
> + bw_flags |= IEEE80211_CHAN_NO_160MHZ;
> + }
> return bw_flags;
> }

--
thomas