linux-kernel - Re: gpio-omap: wakeup mask

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Date:	Tue, 15 Jul 2014 06:41:14 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Pascal Huerst <pascal.huerst@...il.com>
Cc:	santosh.shilimkar@...com, khilman@...prootsystems.com,
	linus.walleij@...aro.org, gnurou@...il.com,
	linux-omap@...r.kernel.org, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org, Daniel Mack <daniel@...que.org>
Subject: Re: gpio-omap: wakeup mask

* Pascal Huerst <pascal.huerst@...il.com> [140715 06:29]:
> 
> 
> On 09.07.2014 17:24, Tony Lindgren wrote:
> > * Pascal Huerst <pascal.huerst@...il.com> [140709 05:47]:
> >> On 09.07.2014 12:41, Tony Lindgren wrote:
> >> 
> >>> If you just comment out the _gpio_rmw part above do things work
> >>> as expected?
> >> 
> >> Yes. It only wakes up on gpio 6 not on gpio 11 anymore.
> >> 
> >>> Then if that works as expected, maybe write only some unused
> >>> bits into wkup_en register and see if it still wakes to all
> >>> events while it should not?
> >> 
> >> If I use the following testcode, everything works as expected:
> >> 
> >> //WARN(true, "WARN: bank->base = %08X\n", bank->base);
> >> 
> >> if (likely(!(bank->non_wakeup_gpios & gpio_bit))) { 
> >> //_gpio_rmw(base, bank->regs->wkup_en, gpio_bit, trigger != 0); 
> >> writel(0xABC00000, base + bank->regs->wkup_en);
> >> 
> >> bank->context.wake_en = readl_relaxed(bank->base + 
> >> bank->regs->wkup_en); printk("bank->base = %08X gpio = %i
> >> bank->context->wake_en = %08X\n", bank->base, gpio,
> >> bank->context.wake_en); }
> > 
> > Hmm weird. It sounds like something like the following is
> > happening:
> > 
> > 1. The first GPIO bank is always powered, and does not need to set 
> > wake-up events
> 
> I dont think so. If I apply my hack (commenting the _gpio_rmw() call)
> and don't have a wakeup source in the dt, I have to reboot the system,
> sonce im not able to wake it up anymore. Or did I miss something?

Well this just from my head without looking at the code, so please
check..

When you comment out the _gpio_rmw() call you are not configuring
any GPIO bank wake-up events.

And the .dts entry just manages the keypad wake-up event for
suspend and resume and does not affect the GPIO bank after you
commented out the _gpio_rmw().
 
> > 2. When setting the GPIO wake-up events it seems that enabling any 
> > wake-up event for the first (16?) bits wakes up the system
> > 
> > You might want to check this with some spare GPIOs not in the first
> > bank and see if you need the wake-up events and if enabling some
> > bits enables more than one GPIO for wake-up events.
> 
> Im not sure if this makes sense, since only the first gpio bank can
> act as a wakeup source. So it should not be possible.

Usually on omaps the first GPIO bank is always powered but also
the other banks can provide wake-up events for most GPIOs
via the IO chain path. I think on am335x, there is no IO chain
path, maybe because of the support for dual voltage IO? So yeah
it could be that only the first GPIO bank can wake up the system
on am335x.

Regards,

Tony
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