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Message-ID: <20120910165856.715f0702@notabene.brown>
Date: Mon, 10 Sep 2012 16:58:56 +1000
From: NeilBrown <neilb@...e.de>
To: balbi@...com
Cc: "Shilimkar, Santosh" <santosh.shilimkar@...com>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Tarun Kanti DebBarma <tarun.kanti@...com>,
Kevin Hilman <khilman@...com>,
Tony Lindgren <tony@...mide.com>, Benoit <b-cousson@...com>,
Grant Likely <grant.likely@...retlab.ca>,
linux-omap@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
Jon Hunter <jon-hunter@...com>
Subject: Re: [PATCH] OMAP GPIO - don't wake from suspend unless requested.
On Thu, 6 Sep 2012 16:26:06 +0300 Felipe Balbi <balbi@...com> wrote:
> Hi,
>
> On Thu, Sep 06, 2012 at 05:02:45PM +1000, NeilBrown wrote:
> > On Thu, 6 Sep 2012 11:18:09 +0530 "Shilimkar, Santosh"
> > <santosh.shilimkar@...com> wrote:
> >
> > > On Thu, Sep 6, 2012 at 8:35 AM, NeilBrown <neilb@...e.de> wrote:
> > > > On Mon, 3 Sep 2012 22:59:06 -0700 "Shilimkar, Santosh"
> > > > <santosh.shilimkar@...com> wrote:
> >
> > > >> After thinking bit more on this, the problem seems to be coming
> > > >> mainly because the gpio device is runtime suspended bit early than
> > > >> it should be. Similar issue seen with i2c driver as well. The i2c issue
> > > >> was discussed with Rafael at LPC last week. The idea is to move
> > > >> the pm_runtime_enable/disable() calls entirely up to the
> > > >> _late/_early stage of device suspend/resume.
> > > >> Will update this thread once I have further update.
> > > >
> > > > This won't be late enough. IRQCHIP_MASK_ON_SUSPEND takes effect after all
> > > > the _late callbacks have been called.
> > > > I, too, spoke to Rafael about this in San Diego. He seemed to agree with me
> > > > that the interrupt needs to be masked in the ->suspend callback. any later
> > > > is too late.
> > > >
> > > Thanks for information about your discussion. Will wait for the patch then.
> > >
> > > Regards
> > > santosh
> >
> > I already sent a patch - that is what started this thread :-)
> >
> > I include it below.
> > You said "The patch doesn't seems to be correct" but didn't expand on why.
> > Do you still think it is not correct? I wouldn't be surprised if there is
> > some case that it doesn't handle quite right, but it seems right to me.
> >
> > Thanks,
> > NeilBrown
> >
> >
> > From: NeilBrown <neilb@...e.de>
> > Subject: [PATCH] OMAP GPIO - don't wake from suspend unless requested.
> >
> > Current kernel will wake from suspend on an event on any active
> > GPIO even if enable_irq_wake() wasn't called.
> >
> > There are two reasons that the hardware wake-enable bit should be set:
> >
> > 1/ while non-suspended the CPU might go into a deep sleep (off_mode)
> > in which the wake-enable bit is needed for an interrupt to be
> > recognised.
> > 2/ while suspended the GPIO interrupt should wake from suspend if and
> > only if irq_wake as been enabled.
> >
> > The code currently doesn't keep these two reasons separate so they get
> > confused and sometimes the wakeup flags is set incorrectly.
> >
> > This patch reverts:
> > commit 9c4ed9e6c01e7a8bd9079da8267e1f03cb4761fc
> > gpio/omap: remove suspend/resume callbacks
> > and
> > commit 0aa2727399c0b78225021413022c164cb99fbc5e
> > gpio/omap: remove suspend_wakeup field from struct gpio_bank
> >
> > and makes some minor changes so that we have separate flags for "GPIO
> > should wake from deep idle" and "GPIO should wake from suspend".
> >
> > With this patch, the GPIO from my touch screen doesn't wake my device
> > any more, which is what I want.
> >
> > Cc: Kevin Hilman <khilman@...com>
> > Cc: Tony Lindgren <tony@...mide.com>
> > Cc: Santosh Shilimkar <santosh.shilimkar@...com>
> > Cc: Cousson Benoit <b-cousson@...com>
> > Cc: Grant Likely <grant.likely@...retlab.ca>
> > Cc: Tarun Kanti DebBarma <tarun.kanti@...com>
> > Cc: Felipe Balbi <balbi@...com>
> > Cc: Govindraj.R <govindraj.raja@...com>
> >
> > Signed-off-by: NeilBrown <neilb@...e.de>
> >
> > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> > index 4fbc208..fdbad70 100644
> > --- a/drivers/gpio/gpio-omap.c
> > +++ b/drivers/gpio/gpio-omap.c
> > @@ -57,6 +57,7 @@ struct gpio_bank {
> > u16 irq;
> > int irq_base;
> > struct irq_domain *domain;
> > + u32 suspend_wakeup;
> > u32 non_wakeup_gpios;
> > u32 enabled_non_wakeup_gpios;
> > struct gpio_regs context;
> > @@ -522,11 +523,12 @@ static int _set_gpio_wakeup(struct gpio_bank *bank, int gpio, int enable)
> >
> > spin_lock_irqsave(&bank->lock, flags);
> > if (enable)
> > - bank->context.wake_en |= gpio_bit;
> > + bank->suspend_wakeup |= gpio_bit;
> > else
> > - bank->context.wake_en &= ~gpio_bit;
> > + bank->suspend_wakeup &= ~gpio_bit;
> >
> > - __raw_writel(bank->context.wake_en, bank->base + bank->regs->wkup_en);
> > + if (!bank->loses_context)
> > + __raw_writel(bank->suspend_wakeup, bank->base + bank->regs->wkup_en);
> > spin_unlock_irqrestore(&bank->lock, flags);
> >
> > return 0;
> > @@ -1157,6 +1159,51 @@ static int __devinit omap_gpio_probe(struct platform_device *pdev)
> > #ifdef CONFIG_ARCH_OMAP2PLUS
> >
> > #if defined(CONFIG_PM_RUNTIME)
> > +
> > +#if defined(CONFIG_PM_SLEEP)
> > +static int omap_gpio_suspend(struct device *dev)
> > +{
> > + struct platform_device *pdev = to_platform_device(dev);
> > + struct gpio_bank *bank = platform_get_drvdata(pdev);
> > + void __iomem *base = bank->base;
> > + unsigned long flags;
> > +
> > + if (!bank->mod_usage || !bank->loses_context)
> > + return 0;
> > +
> > + if (!bank->regs->wkup_en || !bank->context.wake_en)
> > + return 0;
> > +
> > + spin_lock_irqsave(&bank->lock, flags);
>
> shouldn't you be using _noirq methods instead ? Then this would become a
> normal spin_lock()/spin_unlock().
>
I don't think it is appropriate to move functionality between the different
suspend call-backs just because it seems to make the code easier. Each
callback has a purpose and we should stick to that purpose.
The 'suspend' callback should transition the device to a quiescent state,
and I think that includes ensuring that unwanted interrupts won't fire.
'suspend_late' should almost always be the same as runtime_suspend - it
should power-off the device.
'suspend_noirq' ... doesn't seem to have a clear role any more since the
introduction of suspend_late. Hopefully everything will transition over and
suspend_noirq can disappear.
More pragmatically: By the time we get to suspend_noirq, I think the iclk
will have been turned off and so it is too late to try to clear the wkup
flags.
Thanks,
NeilBrown
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