On 21 November 2016 at 15:41, Zefir Kurtisi <zefir.kurtisi@xxxxxxxxxxx> wrote:
> On 11/21/2016 03:04 PM, Benjamin Berg wrote:
>> In the case that a spectral scan is enabled the PHY errors sent by the
>> hardware as part of the scanning might trigger the radar detection and
>> channels might be marked as 'unusable' incorrectly. This patch fixes
>> the issue by preventing the spectral scan to be enabled if DFS is used
>> and only analysing the PHY errors for DFS if radar detection is enabled.
>>
>> [...]
>
> From the relevant source code portion in channel.c:ath_set_channel()
>
> 80 /* Enable radar pulse detection if on a DFS channel. Spectral
> 81 * scanning and radar detection can not be used concurrently.
> 82 */
> 83 if (hw->conf.radar_enabled) {
> 84 u32 rxfilter;
> 85
> 86 rxfilter = ath9k_hw_getrxfilter(ah);
> 87 rxfilter |= ATH9K_RX_FILTER_PHYRADAR |
> 88 ATH9K_RX_FILTER_PHYERR;
> 89 ath9k_hw_setrxfilter(ah, rxfilter);
> 90 ath_dbg(common, DFS, "DFS enabled at freq %d\n",
> 91 chan->center_freq);
> 92 } else {
> 93 /* perform spectral scan if requested. */
> 94 if (test_bit(ATH_OP_SCANNING, &common->op_flags) &&
> 95 sc->spec_priv.spectral_mode == SPECTRAL_CHANSCAN)
> 96 ath9k_cmn_spectral_scan_trigger(common, &sc->spec_priv);
> 97 }
>
> it seems that spectral can't ever be activated while operating on a DFS channel.
>
> If you need to catch the opposite case, i.e. prevent feeding pseudo-radar pulses
> into the pattern detector, you just need to ensure that they depend on
> hw->conf.radar_enabled. A patch like the attached one should be enough.
Good point. I guess set_channel could be oversimplified as well. I
mean, it makes sense to consider radar and spectral mutually exclusive
if they use the same phyerr code. However some chips actually seem (as
per the comment I mentioned) to distinguish the two so I don't know if
the "mutually exclusive" is true for all chips per se. Just thinking
out loud.
I also wonder if calling ieee80211_radar_detect() should have any
effect if there are no radar operated interfaces in the first place?
Michał
