RE: [PATCH rtw-next v5 08/10] wifi: rtw89: handle IEEE80211_TX_CTL_REQ_TX_STATUS frames for USB

[Ping-Ke Shih <pkshih@realtek.com>]

Fedor Pchelkin <pchelkin@ispras.ru> wrote:
> Frames flagged with IEEE80211_TX_CTL_REQ_TX_STATUS mean the driver has to
> report to mac80211 stack whether AP sent ACK for the null frame/probe
> request or not.  It's not implemented in USB part of the driver yet.
> 
> PCIe HCI has its own way of getting TX status incorporated into RPP
> feature, and it's always enabled there.  Other HCIs need a different
> scheme based on processing C2H messages.
> 
> Thus define a .tx_rpt_enabled flag indicating which HCIs need to enable a
> TX report feature.  Currently it is USB only.
> 
> Toggle a bit in the TX descriptor and place flagged skbs in a fix-sized
> queue to wait for a message from the firmware.  Firmware maintains a 4-bit
> sequence number for required frames hence the queue can contain just 16
> elements simultaneously.  That's enough for normal driver / firmware
> communication.  If the firmware crashes for any reason and doesn't provide
> TX reports in time, driver will handle this and report the obsolete frames
> as dropped.
> 
> rtw89 also has a new feature providing a TX report for each transmission
> attempt.  Ignore a failed TX status reported by the firmware until retry
> limit is reached or successful status appears.  When there is no success
> and the retry limit is reached, report the frame up to the wireless stack
> as failed eventually.
> 
> HCI reset should stop all pending TX activity so forcefully flush the
> queue there.
> 
> Found by Linux Verification Center (linuxtesting.org).
> 
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

Acked-by: Ping-Ke Shih <pkshih@realtek.com>