linux-kernel - Re: [PATCH 4.10 012/167] mmc: sdhci-acpi: support deferred probe

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Message-ID: <1490691080.2407.15.camel@intel.com>
Date:   Tue, 28 Mar 2017 16:51:20 +0800
From:   Zhang Rui <rui.zhang@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andrey Utkin <andrey_utkin@...tmail.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Jonas Aaberg <cja@....net>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        kieroglu@...mail.com
Subject: Re: [PATCH 4.10 012/167] mmc: sdhci-acpi: support deferred probe

On Tue, 2017-03-28 at 13:51 +0800, Zhang Rui wrote:
> On Mon, 2017-03-27 at 18:36 +0200, Greg Kroah-Hartman wrote:
> > 
> > On Mon, Mar 27, 2017 at 10:40:23AM +0800, Zhang Rui wrote:
> > > 
> > > 
> > > On Sun, 2017-03-26 at 12:26 +0100, Andrey Utkin wrote:
> > > > 
> > > > 
> > > > On Fri, Mar 10, 2017 at 10:07:35AM +0100, Greg Kroah-Hartman
> > > > wrote:
> > > > > 
> > > > > 
> > > > > 
> > > > > 4.10-stable review patch.  If anyone has any objections,
> > > > > please
> > > > > let
> > > > > me know.
> > > > > 
> > > > > ------------------
> > > > > 
> > > > > From: Zhang Rui <rui.zhang@...el.com>
> > > > > 
> > > > > commit e28d6f048799acb0014491e6b74e580d84bd7916 upstream.
> > > > > 
> > > > > With commit 67bf5156edc4 ("gpio / ACPI: fix returned error
> > > > > from
> > > > > acpi_dev_gpio_irq_get()"), mmc_gpiod_request_cd() returns
> > > > > -EPROBE_DEFER if
> > > > > GPIO is not ready when sdhci-acpi driver is probed, and
> > > > > sdhci-
> > > > > acpi
> > > > > driver
> > > > > should be probed again later in this case.
> > > > > 
> > > > > This fixes an order issue when both GPIO and sdhci-acpi
> > > > > drivers
> > > > > are
> > > > > built
> > > > > as modules.
> > > > > 
> > > > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=177101h
> > > > > tt
> > > > > ps://bugzilla.kernel.org/show_bug.cgi?id=177101
> > > > > Tested-by: Jonas Aaberg <cja@....net>
> > > > > Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> > > > > Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> > > > > Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org
> > > > > >
> > > > > 
> > > > > ---
> > > > >  drivers/mmc/host/sdhci-acpi.c |    5 ++++-
> > > > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > > > 
> > > > > --- a/drivers/mmc/host/sdhci-acpi.c
> > > > > +++ b/drivers/mmc/host/sdhci-acpi.c
> > > > > @@ -467,7 +467,10 @@ static int sdhci_acpi_probe(struct platf
> > > > >  	if (sdhci_acpi_flag(c, SDHCI_ACPI_SD_CD)) {
> > > > >  		bool v = sdhci_acpi_flag(c,
> > > > > SDHCI_ACPI_SD_CD_OVERRIDE_LEVEL);
> > > > >  
> > > > > -		if (mmc_gpiod_request_cd(host->mmc, NULL, 0,
> > > > > v, 0,
> > > > > NULL)) {
> > > > > +		err = mmc_gpiod_request_cd(host->mmc, NULL,
> > > > > 0,
> > > > > v,
> > > > > 0, NULL);
> > > > > +		if (err) {
> > > > > +			if (err == -EPROBE_DEFER)
> > > > > +				goto err_free;
> > > > >  			dev_warn(dev, "failed to setup card
> > > > > detect
> > > > > gpio\n");
> > > > >  			c->use_runtime_pm = false;
> > > > >  		}
> > > > > 
> > > > > 
> > > > Regression reported: https://bugzilla.kernel.org/show_bug.cgi?i
> > > > d=
> > > > 1948
> > > > 71
> > > > 
> > > > Reverting this patch is said to fix the issue for 4.10.2.
> > > thanks for raising the issue. Let's see check why it breaks in
> > > the
> > > bugzilla report.
> > Is this also broken in Linus's tree?
> > 
> Well, I think so.
> 
> Although it's still under debugging, the root cause of the problem
> seems to be that, when mmc_gpiod_request_cd() returns -EPROBE_DEFER,
> it
> means either the GPIO controller driver is not probed at the moment,
> OR
> the GPIO controller driver is not available at all. The later case
>  causes the problem like this because sdhci-acpi driver is made to
> wait
> for the GPIO controller, in the patch above. 
> 
> This is not a problem for distro kernel when all the driver are built
> as modules. And the problem should be fixed by enabling the GPIO
> controller driver in kernel config.
> 
It's confirmed the problem is gone after enabling
CONFIG_PINCTRL_CHERRYVIEW,
https://bugzilla.kernel.org/show_bug.cgi?id=194871#c16

thanks,
rui
> thanks,
> rui