Hi Sascha, On Fri, Mar 31, 2023 at 2:59 PM Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > > On Sun, Jan 08, 2023 at 10:13:22PM +0100, Martin Blumenstingl wrote: > > USB and (upcoming) SDIO support may sleep in the read/write handlers. > > Shrink the RCU critical section so it only cover the call to > > ieee80211_find_sta() and finding the ic_vht_cap/vht_cap based on the > > found station. This moves the chip's BFEE configuration outside the > > rcu_read_lock section and thus prevent "scheduling while atomic" or > > "Voluntary context switch within RCU read-side critical section!" > > warnings when accessing the registers using an SDIO card (which is > > where this issue has been spotted in the real world - but it also > > affects USB cards). > > Unfortunately this introduces a regression on my RTW8821CU chip. With > this it constantly looses connection to the AP and reconnects shortly > after: Sorry to hear this! This is odd and unfortunately I don't understand the reason for this. rtw_bf_assoc() is only called from drivers/net/wireless/realtek/rtw88/mac80211.c with rtwdev->mutex held. So I don't think that it's a race condition. There's a module parameter which lets you enable/disable BF support: $ git grep rtw_bf_support drivers/net/wireless/realtek/rtw88/ | grep param drivers/net/wireless/realtek/rtw88/main.c:module_param_named(support_bf, rtw_bf_support, bool, 0644); Have you tried disabling BF support? Also +Cc Jernej in case he has an idea. Best regards, Martin
