linux-kernel - Re: [PATCH 3/6] gpio/omap: remove suspend_wakeup field from struct gpio

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Message-ID: <CAC83Zv+fiObi8n4OEBeeuP-iPVasipe0N9yNSn-yZXtv5FMgaQ@mail.gmail.com>
Date:	Tue, 28 Feb 2012 16:45:21 +0530
From:	"DebBarma, Tarun Kanti" <tarun.kanti@...com>
To:	Kevin Hilman <khilman@...com>
Cc:	linux-omap@...r.kernel.org, grant.likely@...retlab.ca,
	tony@...mide.com, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/6] gpio/omap: remove suspend_wakeup field from struct gpio_bank

On Tue, Feb 28, 2012 at 3:09 PM, DebBarma, Tarun Kanti
<tarun.kanti@...com> wrote:
> On Tue, Feb 28, 2012 at 5:24 AM, Kevin Hilman <khilman@...com> wrote:
>> Tarun Kanti DebBarma <tarun.kanti@...com> writes:
>>
>>> Since we already have bank->context.wake_en to keep track
>>> of gpios which are wakeup enabled, there is no need to have
>>> this field any more.
>>>
>>> Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@...com>
>>
>> I'm not crazy about this change...
>>
>>> ---
>>>  drivers/gpio/gpio-omap.c |   11 +++++------
>>>  1 files changed, 5 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
>>> index 64f15d5..b62e861 100644
>>> --- a/drivers/gpio/gpio-omap.c
>>> +++ b/drivers/gpio/gpio-omap.c
>>> @@ -53,7 +53,6 @@ struct gpio_bank {
>>>       void __iomem *base;
>>>       u16 irq;
>>>       u16 virtual_irq_start;
>>> -     u32 suspend_wakeup;
>>>       u32 non_wakeup_gpios;
>>>       u32 enabled_non_wakeup_gpios;
>>>       struct gpio_regs context;
>>> @@ -497,9 +496,9 @@ static int _set_gpio_wakeup(struct gpio_bank *bank, int gpio, int enable)
>>>
>>>       spin_lock_irqsave(&bank->lock, flags);
>>>       if (enable)
>>> -             bank->suspend_wakeup |= gpio_bit;
>>> +             bank->context.wake_en |= gpio_bit;
>>>       else
>>> -             bank->suspend_wakeup &= ~gpio_bit;
>>> +             bank->context.wake_en &= ~gpio_bit;
>>
>> The bank->context values are expected to be copies of the actual
>> register contents, and here that is clearly not the case.
> Right, it should have been this:
>
>        if (enable)
> -               bank->suspend_wakeup |= gpio_bit;
> +               bank->context.wake_en |= gpio_bit;
>        else
> -               bank->suspend_wakeup &= ~gpio_bit;
> +               bank->context.wake_en &= ~gpio_bit;
> +
> +       __raw_writel(bank->context.wake_en, bank->base + bank->regs->wkup_en);
>
>>
>> With this change, you're using the context register to track changes
>> that you *might* eventually write to the register.
> The above change ensures that bank->context.wake_en reflects the
> latest register value.
> There are two distinct paths through which bank->context.wake_en is
> updated now, viz:
> Path1:-
> chip.irq_set_type() --> gpio_irq_type() --> _set_gpio_triggering() -->
> set_gpio_trigger()
>
> Path2:-
> chip.irq_set_wake() --> gpio_wake_enable() --> irq_set_wake()
Sorry, it should have been:
chip.irq_set_wake() --> gpio_wake_enable() --> _set_gpio_wakeup()

>
>>
>> IMO, this is more confusing than having a separate field to track this.
> So, there is no need have a separate field to keep track of this.
> I hope my understanding is right.
> --
> Tarun
>
>>
>> Kevin
>>
>>>       spin_unlock_irqrestore(&bank->lock, flags);
>>>
>>> @@ -772,7 +771,7 @@ static int omap_mpuio_suspend_noirq(struct device *dev)
>>>
>>>       spin_lock_irqsave(&bank->lock, flags);
>>>       bank->context.wake_en = __raw_readl(mask_reg);
>>> -     __raw_writel(0xffff & ~bank->suspend_wakeup, mask_reg);
>>> +     __raw_writel(0xffff & ~bank->context.wake_en, mask_reg);
>>>       spin_unlock_irqrestore(&bank->lock, flags);
>>>
>>>       return 0;
>>> @@ -1137,12 +1136,12 @@ static int omap_gpio_suspend(struct device *dev)
>>>       if (!bank->mod_usage || !bank->loses_context)
>>>               return 0;
>>>
>>> -     if (!bank->regs->wkup_en || !bank->suspend_wakeup)
>>> +     if (!bank->regs->wkup_en || !bank->context.wake_en)
>>>               return 0;
>>>
>>>       spin_lock_irqsave(&bank->lock, flags);
>>>       _gpio_rmw(base, bank->regs->wkup_en, 0xffffffff, 0);
>>> -     _gpio_rmw(base, bank->regs->wkup_en, bank->suspend_wakeup, 1);
>>> +     _gpio_rmw(base, bank->regs->wkup_en, bank->context.wake_en, 1);
>>>       spin_unlock_irqrestore(&bank->lock, flags);
>>>
>>>       return 0;
--
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