On Fri, 2017-09-08 at 10:43 +0200, Richard Schütz wrote:

Am 08.09.2017 um 08:55 schrieb Johannes Berg:

quoted

On Thu, 2017-09-07 at 17:47 +0200, Richard Schütz wrote:

quoted

Use IEEE80211_RATE_MANDATORY_G instead of
IEEE80211_RATE_MANDATORY_B
for comparison to get all mandatory rates in 2.4 GHz band. It is
safe
to do so because ERP mandatory rates are a superset of HR/DSSS
mandatory rates.

This I don't understand - what "comparison" are you talking about?

Sorry, I meant the condition that checks for the presence of 
mandatory_flag at the bottom of the function.

Ah, sorry, I got confused with the other patch.

Do we actually allow 10 MHz and 5 MHz operation in the 2.4 GHz band?
As  far as I can tell that has only been specified for OFDM PHYs,
which use the 5 GHz band and are covered by
IEEE80211_RATE_MANDATORY_A, but I am not a hundred per cent sure
about that. Cc'ing Simon Wunderlich who originally implemented
checking of scan_width here.

Clearly we do allow that, since the existing check is:

        if (sband->band == NL80211_BAND_2GHZ) {
                if (scan_width == NL80211_BSS_CHAN_WIDTH_5 ||
                    scan_width == NL80211_BSS_CHAN_WIDTH_10)
                        mandatory_flag = IEEE80211_RATE_MANDATORY_G;

That wouldn't make any sense if we didn't have 5/10 MHz on 2.4 GHz.

The main intention of this patch series is to fix mandatory rates 
returned for normal operation in 2.4 GHz band. Currently only 1 Mb/s
is returned here, which is wrong for both HR/DSSS and ERP PHYs.

The patch is still wrong wrt. 5/10 MHz though.

I think what you really wanted to do is the following:

 * rename RATE_MANDATORY_B to RATE_MANDATORY_HR_DSSS
 * combine RATE_MANDATORY_G/_A to RATE_MANDATORY_OFDM

Then, what you need to do, is change the checks in
ieee80211_mandatory_rates() to be

        if (sband->band == NL80211_BAND_2GHZ) {
                if (scan_width == NL80211_BSS_CHAN_WIDTH_5 ||
                    scan_width == NL80211_BSS_CHAN_WIDTH_10)
                        mandatory_flag = IEEE80211_RATE_MANDATORY_OFDM;
                else
                        mandatory_flag = IEEE80211_RATE_MANDATORY_HR_DSSS;
        } else {
                mandatory_flag = IEEE80211_RATE_MANDATORY_OFDM;
        }

That would actually fix a bug in a way because right now the code
treats HR/DSSS rates (1, 2, 5.5, 11) for 2.4 GHz narrow-band operation
as mandatory, which seems wrong.

johannes