On Thu, Mar 15, 2018 at 2:30 PM, Kalle Valo <kvalo@xxxxxxxxxxxxxx> wrote: > Amitkumar Karwar <amitkarwar@xxxxxxxxx> writes: > >> On Tue, Mar 13, 2018 at 8:46 PM, Kalle Valo <kvalo@xxxxxxxxxxxxxx> wrote: >>> Amitkumar Karwar <amitkarwar@xxxxxxxxx> writes: >>> >>>> From: Prameela Rani Garnepudi <prameela.j04cs@xxxxxxxxx> >>>> >>>> With the current approach of scanning, roaming delays >>>> are observed. Firmware has support for back ground scanning. >>>> To get this advantage, mac80211 hardware scan is implemented. >>>> In this method, foreground scan is performed in driver and >>>> back ground scan is configured to firmware. >>> >>> To me doesn't like a good idea to duplicate scan functionality in the >>> driver. >> >> There is a limitation with our device. We need to configure background >> scan parameters to firmware when device is connected. > > Yeah, I guessed that. > >> In non-connected state, we can directly dump probe requests received >> from mac80211 as a part of software scan. Some synchronization issues >> are with existing software scan when device is connected. This patch >> implements hw_scan where these issues are no seen, as driver has more >> control on scan state machine > > What I don't like here is that you are duplicating functionality already > existing in mac80211 and I hope there is a better way to solve the > problem. Just as a a crazy idea what if the driver returns -EOPNOTSUPP > when hardware scan is not possible and mac80211 falls back to software > scan? But of course this depends on what Johannes thinks. Currently mac80211 offloads scan to driver if "ops->hw_scan" is implemented. Otherwise falls back to software scan. I can see below vendors have already implemented hw_scan with their own scan state machine. This patch does the same thing. Let me know if I missed anything here. /ath/ath10k/mac.c:7684: .hw_scan = ath10k_hw_scan, ./ath/wcn36xx/main.c:1115: .hw_scan = wcn36xx_hw_scan, ./ath/ath9k/main.c:2626: ath9k_ops.hw_scan = ath9k_hw_scan; ./st/cw1200/main.c:215: .hw_scan = cw1200_hw_scan, ./atmel/at76c50x-usb.c:2195: .hw_scan = at76_hw_scan, ./ti/wl1251/main.c:1376: .hw_scan = wl1251_op_hw_scan, ./ti/wlcore/main.c:5923: .hw_scan = wl1271_op_hw_scan, ./intel/iwlegacy/3945-mac.c:3485: .hw_scan = il_mac_hw_scan, ./intel/iwlegacy/3945-mac.c:3915: il3945_mac_ops.hw_scan = NULL; ./intel/iwlegacy/4965-mac.c:6352: .hw_scan = il_mac_hw_scan, ./intel/iwlwifi/mvm/mac80211.c:4343: .hw_scan = iwl_mvm_mac_hw_scan, ./intel/iwlwifi/dvm/mac80211.c:1627: .hw_scan = iwlagn_mac_hw_scan, ./mac80211_hwsim.c:2390: .hw_scan = mac80211_hwsim_hw_scan, Regards, Amitkumar
