staging: wfx: ensure HIF request has been sent before polling
wfx_bh_request_tx() send HIF request asynchronously through bh_work().
Then the caller will run wfx_bh_poll_irq() to poll the answer.
However it useless to burn CPU cycles for the polling while the request
has yet been sent. Worse, wfx_bh_poll_irq() may get the CPU and prevent
wfx_bh_request_tx() to run. This problem has been observed on mono core
architecture.
This first exchange is correct:
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003000
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003000
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003004
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003004
kworker/0:1H-40 [000] .... : io_read: QUEUE: 08 00 09 0c 00 00 00 00 3a 7b 00 30 (12 bytes)
kworker/0:1H-40 [000] .... : piggyback: CONTROL:
00003000
kworker/0:1H-40 [000] .... : hif_recv: 0:2:CNF_CONFIGURATION: 00 00 00 00 (8 bytes)
kworker/0:1H-40 [000] .... : io_read32: CONFIG:
03010200
kworker/0:1H-40 [000] .... : bh_stats: IND/REQ/CNF: 0/ 0/ 1, REQ in progress: 0, WUP: release
... while the following is not:
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003000
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003000
kworker/u2:1-24 [000] .... : io_read32: CONTROL:
00003000
[...loop until timeout...]
wfx-sdio mmc0:0001:1: time out while polling control register
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220225112405.355599-10-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>