Re: [PATCH 1/3] brcmfmac: re-enable command decode in sdio_aos for BRCM 4354

From: Doug Anderson <dianders@chromium.org>
To: Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
	Kalle Valo <kvalo@codeaurora.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Double Lo <double.lo@cypress.com>,
	Brian Norris <briannorris@chromium.org>,
	Madhan Mohan R <madhanmohan.r@cypress.com>,
	Matthias Kaehlcke <mka@chromium.org>,
	Wright Feng <wright.feng@cypress.com>,
	Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
	brcm80211-dev-list.pdl@broadcom.com,
	Franky Lin <franky.lin@broadcom.com>,
	netdev <netdev@vger.kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Hante Meuleman <hante.meuleman@broadcom.com>,
	Naveen Gupta <naveen.gupta@cypress.com>,
	brcm80211-dev-list@cypress.com,
	YueHaibing <yuehaibing@huawei.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH 1/3] brcmfmac: re-enable command decode in sdio_aos for BRCM 4354
Date: Mon, 20 May 2019 11:20:22 -0700	[thread overview]
Message-ID: <CAD=FV=Uvc1wUQe-W1Jvm_gQ722pFm2a4OWvJDNVtkyQynFe4Gw@mail.gmail.com> (raw)
In-Reply-To: <e3f54bcb-8d10-1336-1458-2bd11cfc1010@broadcom.com>

Hi,

On Mon, May 20, 2019 at 1:09 AM Arend Van Spriel
<arend.vanspriel@broadcom.com> wrote:
>
> On 5/18/2019 12:54 AM, Douglas Anderson wrote:
> > In commit 29f6589140a1 ("brcmfmac: disable command decode in
> > sdio_aos") we disabled something called "command decode in sdio_aos"
> > for a whole bunch of Broadcom SDIO WiFi parts.
> >
> > After that patch landed I find that my kernel log on
> > rk3288-veyron-minnie and rk3288-veyron-speedy is filled with:
> >    brcmfmac: brcmf_sdio_bus_sleep: error while changing bus sleep state -110
> >
> > This seems to happen every time the Broadcom WiFi transitions out of
> > sleep mode.  Reverting the part of the commit that affects the WiFi on
> > my boards fixes the problem for me, so that's what this patch does.
>
> This sounds very similar to the issue we had during integration of wifi
> on rk3288 chromebooks years ago.

I'm working on those same Chromebooks.  ;-)  I'm working on trying to
make them well on newer kernels.

...but I guess you're saying that the problem faced by the people who
wanted commit 29f6589140a1 ("brcmfmac: disable command decode in
sdio_aos") are similar to the problems we saw in the past on those
Chromebooks.  I'd tend to agree.  In general it's difficult to get a
SD Host Controller to be fully robust in the fact of any/all errors on
the bus.  While dw_mmc is pretty robust these days I'm assuming that
some other host controllers aren't.

> > Note that, in general, the justification in the original commit seemed
> > a little weak.  It looked like someone was testing on a SD card
> > controller that would sometimes die if there were CRC errors on the
> > bus.  This used to happen back in early days of dw_mmc (the controller
> > on my boards), but we fixed it.  Disabling a feature on all boards
> > just because one SD card controller is broken seems bad.  ...so
> > instead of just this patch possibly the right thing to do is to fully
> > revert the original commit.
>
> I am leaning towards a full revert, but let's wait for more background info.

I'd be fine with a full revert too.  Presumably that will break
someone but maybe they need to come up with a better solution?

-Doug