mt76 tx status

[Johannes Stezenbach <js@sig21.net>]

Hi Felix,

I noticed in mt76x2_mac_poll_tx_status() you are reading
MT_TX_STAT_FIFO before reading MT_TX_STAT_FIFO_EXT,
however I have a hunch that reading MT_TX_STAT_FIFO clobbers
the corresponding MT_TX_STAT_FIFO_EXT since MT_TX_STAT_FIFO
has the valid bit, and both registers together seem to implement
reading a 64bit FIFO entry.  I.e. you need to read
MT_TX_STAT_FIFO_EXT first otherwise you get a mix from
two FIFO entries.

I played a bit with the vendor driver for the mt7610u
and confirmed that multiple reads from MT_TX_STAT_FIFO_EXT
return the same value until MT_TX_STAT_FIFO is read.
(Note the mt7610u vendor driver does not define FIFO_EXT_SUPPORT
but the FIFO seems to exist in hardware.  The mt7612u vendor driver
code reads the MT_TX_STAT_FIFO_EXT first.)


Johannes