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From: Arend Van Spriel <arend.vanspriel@broadcom.com>
To: Douglas Anderson <dianders@chromium.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Kalle Valo <kvalo@codeaurora.org>,
	Adrian Hunter <adrian.hunter@intel.com>
Cc: brcm80211-dev-list.pdl@broadcom.com,
	linux-rockchip@lists.infradead.org,
	Double Lo <double.lo@cypress.com>,
	briannorris@chromium.org, linux-wireless@vger.kernel.org,
	Naveen Gupta <naveen.gupta@cypress.com>,
	Madhan Mohan R <madhanmohan.r@cypress.com>,
	mka@chromium.org, Wright Feng <wright.feng@cypress.com>,
	Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
	netdev@vger.kernel.org, brcm80211-dev-list@cypress.com,
	Franky Lin <franky.lin@broadcom.com>,
	linux-kernel@vger.kernel.org,
	Hante Meuleman <hante.meuleman@broadcom.com>,
	YueHaibing <yuehaibing@huawei.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v4 5/5] brcmfmac: sdio: Don't tune while the card is off
Date: Mon, 17 Jun 2019 12:52:51 +0200
Message-ID: <f0dc6ef8-b339-8656-14d6-cf7c4e872b22@broadcom.com> (raw)
In-Reply-To: <20190613234153.59309-6-dianders@chromium.org>

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

      parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13 23:41 [PATCH v4 0/5] brcmfmac: sdio: Deal better w/ transmission errors related to idle Douglas Anderson
2019-06-13 23:41 ` [PATCH v4 1/5] Revert "brcmfmac: disable command decode in sdio_aos" Douglas Anderson
2019-06-13 23:41 ` [PATCH v4 2/5] mmc: core: API to temporarily disable retuning for SDIO CRC errors Douglas Anderson
2019-06-14 12:04   ` Ulf Hansson
2019-06-14 16:41     ` Doug Anderson
2019-06-17  7:53       ` Ulf Hansson
2019-06-17  8:30   ` Adrian Hunter
2019-06-13 23:41 ` [PATCH v4 3/5] brcmfmac: sdio: Disable auto-tuning around commands expected to fail Douglas Anderson
2019-06-17  8:33   ` Adrian Hunter
2019-06-17 10:35   ` Arend Van Spriel
2019-06-13 23:41 ` [PATCH v4 4/5] mmc: core: Add sdio_retune_hold_now() and sdio_retune_release() Douglas Anderson
2019-06-14 12:09   ` Ulf Hansson
2019-06-14 16:38     ` Doug Anderson
2019-06-14 17:17       ` Arend Van Spriel
2019-06-17  8:46       ` Adrian Hunter
2019-06-17  8:34   ` Adrian Hunter
2019-06-13 23:41 ` [PATCH v4 5/5] brcmfmac: sdio: Don't tune while the card is off Douglas Anderson
2019-06-17  8:28   ` Adrian Hunter
2019-06-17 10:52   ` Arend Van Spriel [this message]

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