Linux-Wireless Archive on lore.kernel.org
 help / color / Atom feed
From: Ulf Hansson <ulf.hansson@linaro.org>
To: Doug Anderson <dianders@chromium.org>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Ganapathi Bhat <gbhat@marvell.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Andreas Fenkart <afenkart@gmail.com>,
	Brian Norris <briannorris@chromium.org>,
	Amitkumar Karwar <amitkarwar@gmail.com>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Nishant Sarmukadam <nishants@marvell.com>,
	netdev <netdev@vger.kernel.org>,
	Avri Altman <avri.altman@wdc.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Xinming Hu <huxinming820@gmail.com>,
	Matthias Kaehlcke <mka@chromium.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Kate Stewart <kstewart@linuxfoundation.org>
Subject: Re: [PATCH v2 1/2] mmc: core: Add sdio_trigger_replug() API
Date: Thu, 17 Oct 2019 11:10:21 +0200
Message-ID: <CAPDyKFrwUgi6MzyZm0VgGWOahCGW6KgGRrWC7v=KvM=vbFY4RA@mail.gmail.com> (raw)
In-Reply-To: <CAD=FV=WTKy3PmMSCbjKA_Ro_MP+dFE89oCzi_Bs7YeCrcD+3Xg@mail.gmail.com>

On Thu, 17 Oct 2019 at 02:22, Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Thu, Oct 10, 2019 at 7:11 AM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > On Mon, 22 Jul 2019 at 21:41, Douglas Anderson <dianders@chromium.org> wrote:
> > >
> > > When using Marvell WiFi SDIO cards, it is not uncommon for Linux WiFi
> > > driver to fully lose the communication channel to the firmware running
> > > on the card.  Presumably the firmware on the card has a bug or two in
> > > it and occasionally crashes.
> > >
> > > The Marvell WiFi driver attempts to recover from this problem.
> > > Specifically the driver has the function mwifiex_sdio_card_reset()
> > > which is called when communcation problems are found.  That function
> > > attempts to reset the state of things by utilizing the mmc_hw_reset()
> > > function.
> > >
> > > The current solution is a bit complex because the Marvell WiFi driver
> > > needs to manually deinit and reinit the WiFi driver around the reset
> > > call.  This means it's going through a bunch of code paths that aren't
> > > normally tested.  However, complexity isn't our only problem.  The
> > > other (bigger) problem is that Marvell WiFi cards are often combo
> > > WiFi/Bluetooth cards and Bluetooth runs on a second SDIO func.  While
> > > the WiFi driver knows that it should re-init its own state around the
> > > mmc_hw_reset() call there is no good way to inform the Bluetooth
> > > driver.  That means that in Linux today when you reset the Marvell
> > > WiFi driver you lose all Bluetooth communication.  Doh!
> >
> > Thanks for a nice description to the problem!
> >
> > In principle it makes mmc_hw_reset() quite questionable to use for
> > SDIO func drivers, at all. However, let's consider that for later.
>
> Yeah, unless you somehow knew that your card would only have one function.
>
>
> > > One way to fix the above problems is to leverage a more standard way
> > > to reset the Marvell WiFi card where we go through the same code paths
> > > as card unplug and the card plug.  In this patch we introduce a new
> > > API call for doing just that: sdio_trigger_replug().  This API call
> > > will trigger an unplug of the SDIO card followed by a plug of the
> > > card.  As part of this the card will be nicely reset.
> >
> > I have been thinking back and forth on this, exploring various
> > options, perhaps adding some callbacks that the core could invoke to
> > inform the SDIO func drivers of what is going on.
> >
> > Although, in the end this boils done to complexity and I think your
> > approach is simply the most superior in regards to this. However, I
> > think there is a few things that we can do to even further simply your
> > approach, let me comment on the code below.
>
> Right.  Unplugging / re-plugging is sorta gross / inelegant, but it is
> definitely simpler and nice that it doesn't add so many new code
> paths.  For cases where you're just trying to re-init things with a
> hammer it works pretty well.
>
>
> > > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > > Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> > > ---
> > >
> > > Changes in v2:
> > > - s/routnine/routine (Brian Norris, Matthias Kaehlcke).
> > > - s/contining/containing (Matthias Kaehlcke).
> > > - Add Matthias Reviewed-by tag.
> > >
> > >  drivers/mmc/core/core.c       | 28 ++++++++++++++++++++++++++--
> > >  drivers/mmc/core/sdio_io.c    | 20 ++++++++++++++++++++
> > >  include/linux/mmc/host.h      | 15 ++++++++++++++-
> > >  include/linux/mmc/sdio_func.h |  2 ++
> > >  4 files changed, 62 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > > index 221127324709..5da365b1fdb4 100644
> > > --- a/drivers/mmc/core/core.c
> > > +++ b/drivers/mmc/core/core.c
> > > @@ -2161,6 +2161,12 @@ int mmc_sw_reset(struct mmc_host *host)
> > >  }
> > >  EXPORT_SYMBOL(mmc_sw_reset);
> > >
> > > +void mmc_trigger_replug(struct mmc_host *host)
> > > +{
> > > +       host->trigger_replug_state = MMC_REPLUG_STATE_UNPLUG;
> > > +       _mmc_detect_change(host, 0, false);
> > > +}
> > > +
> > >  static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
> > >  {
> > >         host->f_init = freq;
> > > @@ -2214,6 +2220,11 @@ int _mmc_detect_card_removed(struct mmc_host *host)
> > >         if (!host->card || mmc_card_removed(host->card))
> > >                 return 1;
> > >
> > > +       if (host->trigger_replug_state == MMC_REPLUG_STATE_UNPLUG) {
> > > +               mmc_card_set_removed(host->card);
> > > +               return 1;
> >
> > Do you really need to set state of the card to "removed"?
> >
> > If I understand correctly, what you need is to allow mmc_rescan() to
> > run a second time, in particular for non removable cards.
> >
> > In that path, mmc_rescan should find the card being non-functional,
> > thus it should remove it and then try to re-initialize it again. Etc.
> >
> > Do you want me to send a patch to show you what I mean!?
>
> If you don't mind, that would probably be easiest.  I've totally
> swapped out all of the implementation details of this from my brain
> now, but if I saw a patch from you it would be easy for me to analyze
> it and test it.

Alright, I think I owe you that because of my slow review pase. :-)

Patches are coming soon!

Kind regards
Uffe

  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-22 19:39 [PATCH v2 0/2] mmc: core: Fix Marvell WiFi reset by adding SDIO API to replug card Douglas Anderson
2019-07-22 19:39 ` [PATCH v2 1/2] mmc: core: Add sdio_trigger_replug() API Douglas Anderson
2019-10-10 14:10   ` Ulf Hansson
2019-10-17  0:22     ` Doug Anderson
2019-10-17  9:10       ` Ulf Hansson [this message]
2019-07-22 19:39 ` [PATCH v2 2/2] mwifiex: Make use of the new sdio_trigger_replug() API to reset Douglas Anderson
2019-07-24 11:35   ` Kalle Valo
     [not found]   ` <20190724113508.47A356021C@smtp.codeaurora.org>
2019-07-24 20:22     ` Doug Anderson
2019-07-25  5:56       ` Kalle Valo
2019-07-25 13:28 ` [PATCH v2 0/2] mmc: core: Fix Marvell WiFi reset by adding SDIO API to replug card Ulf Hansson
2019-09-11 21:26   ` Doug Anderson
2019-09-16  9:25     ` Ulf Hansson
2019-10-07 23:39       ` Doug Anderson
2019-10-08 11:49         ` Ulf Hansson
2019-07-30  8:46 ` Andreas Fenkart
2019-07-30 16:59   ` Doug Anderson

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAPDyKFrwUgi6MzyZm0VgGWOahCGW6KgGRrWC7v=KvM=vbFY4RA@mail.gmail.com' \
    --to=ulf.hansson@linaro.org \
    --cc=adrian.hunter@intel.com \
    --cc=afenkart@gmail.com \
    --cc=amitkarwar@gmail.com \
    --cc=avri.altman@wdc.com \
    --cc=briannorris@chromium.org \
    --cc=davem@davemloft.net \
    --cc=dianders@chromium.org \
    --cc=gbhat@marvell.com \
    --cc=huxinming820@gmail.com \
    --cc=kstewart@linuxfoundation.org \
    --cc=kvalo@codeaurora.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mmc@vger.kernel.org \
    --cc=linux-rockchip@lists.infradead.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=mka@chromium.org \
    --cc=netdev@vger.kernel.org \
    --cc=nishants@marvell.com \
    --cc=tglx@linutronix.de \
    --cc=wsa+renesas@sang-engineering.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Wireless Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-wireless/0 linux-wireless/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-wireless linux-wireless/ https://lore.kernel.org/linux-wireless \
		linux-wireless@vger.kernel.org
	public-inbox-index linux-wireless

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-wireless


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git