Messages in this thread | | | Subject | Re: [PATCH v4 5/5] brcmfmac: sdio: Don't tune while the card is off | From | Arend Van Spriel <> | Date | Mon, 17 Jun 2019 12:52:51 +0200 |
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On 6/14/2019 1:41 AM, Douglas Anderson wrote: > When Broadcom SDIO cards are idled they go to sleep and a whole > separate subsystem takes over their SDIO communication. This is the > Always-On-Subsystem (AOS) and it can't handle tuning requests. > > Specifically, as tested on rk3288-veyron-minnie (which reports having > BCM4354/1 in dmesg), if I force a retune in brcmf_sdio_kso_control() > when "on = 1" (aka we're transition from sleep to wake) by whacking: > bus->sdiodev->func1->card->host->need_retune = 1 > ...then I can often see tuning fail. In this case dw_mmc reports "All > phases bad!"). Note that I don't get 100% failure, presumably because > sometimes the card itself has already transitioned away from the AOS > itself by the time we try to wake it up. If I force retuning when "on > = 0" (AKA force retuning right before sending the command to go to > sleep) then retuning is always OK. > > NOTE: we need _both_ this patch and the patch to avoid triggering > tuning due to CRC errors in the sleep/wake transition, AKA ("brcmfmac: > sdio: Disable auto-tuning around commands expected to fail"). Though > both patches handle issues with Broadcom's AOS, the problems are > distinct: > 1. We want to defer (but not ignore) asynchronous (like > timer-requested) tuning requests till the card is awake. However, > we want to ignore CRC errors during the transition, we don't want > to queue deferred tuning request. > 2. You could imagine that the AOS could implement retuning but we > could still get errors while transitioning in and out of the AOS. > Similarly you could imagine a seamless transition into and out of > the AOS (with no CRC errors) even if the AOS couldn't handle > tuning. > > ALSO NOTE: presumably there is never a desperate need to retune in > order to wake up the card, since doing so is impossible. Luckily the > only way the card can get into sleep state is if we had a good enough > tuning to send it a sleep command, so presumably that "good enough" > tuning is enough to wake us up, at least with a few retries.
The term "sleep command" is a bit confusing. There actually is a CMD14 defined in the eSD spec, but that is not what we are using (unless we program the chip to do so) here. It is simply a specific register access using CMD52.
Apart from that....
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com> > > Signed-off-by: Douglas Anderson <dianders@chromium.org>
I think the stable version is mostly determined by change in MMC/SDIO so 4.18 as mentioned Adrian seems most sensible. bcm4354 support was introduced in 3.14 and there were some earlier devices (4335) using same sleep mechanism.
Regards, Arend
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