Re: [PATCH rtw-next v3] wifi: rtw88: usb: route bmc frames via the high queue only for DTIM delivery

[Mehmet Fide <mehmet.fide@gmail.com>]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

Hello Ping-Ke,

One more data point that may be useful for the firmware side,
separate from this patch.

While comparing against the vendor driver I noticed a difference in
how MORE_DATA is terminated. rtw88 sets the bit on every high queue
frame (rtw_tx_fill_tx_desc(): more_data = qsel == TX_DESC_QSEL_HIGH),
including the last one. The vendor driver releases the high queue as
an explicit batch and sets mdata = 1 on all frames of the batch
except the final one, which carries 0 (chk_bmc_sleepq_hdl() in
core/rtw_mlme_ext.c of the 88x2bu source).

On both RTL8822BU and RTL8821CU I measured the high queue draining at
roughly 3 frames per DTIM with BIT_TCR_UPDATE_HGQMD set, instead of
the whole buffered burst, so the burst fetch of 076f786a0ae1 does not
seem to engage on these chips. A never-terminated MORE_DATA chain is
my best guess for why, but that is a guess; whether the hardware
needs the 0 to conclude a burst is something only the firmware
documentation can answer.

Thanks,
Mehmet