[PATCH v2 0/3] brcmfmac: sdio: Deal better w/ transmission errors waking from idle

From: Douglas Anderson
Date: Mon Jun 03 2019 - 14:41:49 EST

This series attempts to deal better with the expected transmission
errors that we get when waking up (from idle) the SDIO-based WiFi on
rk3288-veyron-minnie, rk3288-veyron-speedy, and rk3288-veyron-mickey.

Some details about those errors can be found in
<https://crbug.com/960222>, but to summarize it here: if we try to
send the wakeup command to the WiFi card at the same time it has
decided to wake up itself then it will behave badly on the SDIO bus.
This can cause timeouts or CRC errors.

When I tested on 4.19 and 4.20 these CRC errors can be seen to cause
re-tuning. Since I am currently developing on 4.19 this was the
original problem I attempted to solve.

On mainline it turns out that you don't see the retuning errors but
you see tons of spam about timeouts trying to wakeup from sleep. I
tracked down the commit that was causing that and have partially
reverted it here. I have no real knowledge about Broadcom WiFi, but
the commit that was causing problems sounds (from the descriptioin) to
be a hack commit penalizing all Broadcom WiFi users because of a bug
in a Cypress SD controller. I will let others comment if this is
truly the case and, if so, what the right solution should be.

There wasn't a good resolution on v1 and it's been a while, so I'm
sending out a v2. Other than changing patch #1 to a full revert, the
only other changes here are just to the patch descriptions.

Changes in v2:
- A full revert, not just a partial one (Arend). ...with explicit Cc.
- Updated commit message to clarify based on discussion of v1.

Douglas Anderson (3):
Revert "brcmfmac: disable command decode in sdio_aos"
mmc: core: API for temporarily disabling auto-retuning due to errors
brcmfmac: sdio: Disable auto-tuning around commands expected to fail

drivers/mmc/core/core.c | 27 +++++++++++++++++--
.../broadcom/brcm80211/brcmfmac/sdio.c | 9 +++----
include/linux/mmc/core.h | 2 ++
include/linux/mmc/host.h | 1 +
4 files changed, 32 insertions(+), 7 deletions(-)