[0/3] brcmfmac: sdio: Deal better w/ transmission errors waking from sleep

Message

Doug Anderson May 17, 2019, 10:54 p.m. UTC

This series attempts to deal better with the expected transmission
errors that we get when waking up 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.


Douglas Anderson (3):
  brcmfmac: re-enable command decode in sdio_aos for BRCM 4354
  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        |  6 +++--
 include/linux/mmc/core.h                      |  2 ++
 include/linux/mmc/host.h                      |  1 +
 4 files changed, 32 insertions(+), 4 deletions(-)

Comments

Avri Altman May 18, 2019, 3:09 p.m. UTC | #1

> 
> This series attempts to deal better with the expected transmission
> errors that we get when waking up 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.
Wake-up itself: as part of a WoWlan, or d0i3?
Looks like this calls for a wifi driver fix, and not WA in the mmc driver.

Thanks,
Avri

Arend van Spriel May 20, 2019, 8:55 a.m. UTC | #2

On 5/18/2019 12:54 AM, Douglas Anderson wrote:
> This series attempts to deal better with the expected transmission
> errors that we get when waking up 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.

Let me give a bit of background. The brcmfmac driver implements its own 
runtime-pm like functionality, ie. if the driver is idle for some time 
it will put the device in a low-power state. When it does that it powers 
down several cores in the chip among which the SDIO core. However, the 
SDIO bus used be very bad at handling devices that do that so instead it 
has the Always-On-Station (AOS) block take over the SDIO core in 
handling the bus. Default is will send a R1 response, but only for CMD52 
(and CMD14 but no host is using that cruft). In noCmdDecode it does not 
respond and simply wakes up the SDIO core, which takes over again. 
Because it does not respond timeouts (-110) are kinda expected in this mode.

Regards,
Arend

Brian Norris May 21, 2019, 12:23 a.m. UTC | #3

On Sat, May 18, 2019 at 03:09:44PM +0000, Avri Altman wrote:
> > 
> > This series attempts to deal better with the expected transmission
> > errors that we get when waking up 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.
> Wake-up itself: as part of a WoWlan, or d0i3?

Neither, IIUC. (It's definitely not WoWLAN, and D0i3 sounds like an
Intel thing.)

I believe it's a Broadcom-specific mode. See also Arend's response to
this thread:

http://lkml.kernel.org/linux-wireless/[e-mail]

> Looks like this calls for a wifi driver fix, and not WA in the mmc driver.

Basically asked and answered in patch 2's thread:

https://lkml.kernel.org/lkml/20190520085201.GA1021@kunai/