linux-kernel - Re: [PATCH] pinctrl: intel: Clear interrupt status in unmask callback

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Message-Id: <6BCF9C55-E365-4638-8030-99EBA348F8D4@canonical.com>
Date:   Mon, 29 Apr 2019 17:16:16 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     mika.westerberg@...ux.intel.com, linus.walleij@...aro.org,
        hotwater438@...anota.com, hdegoede@...hat.com,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: intel: Clear interrupt status in unmask callback

at 05:47, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On Mon, Apr 22, 2019 at 12:45:39PM +0800, Kai-Heng Feng wrote:
>> Commit a939bb57cd47 ("pinctrl: intel: implement gpio_irq_enable") was
>> added because clearing interrupt status bit is required to avoid
>> unexpected behavior.
>>
>> Turns out the unmask callback also needs the fix, which can solve weird
>> IRQ triggering issues on I2C touchpad ELAN1200.
>
>> -static void intel_gpio_irq_enable(struct irq_data *d)
>> -{
>> -	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>> -	struct intel_pinctrl *pctrl = gpiochip_get_data(gc);
>> -	const struct intel_community *community;
>> -	const struct intel_padgroup *padgrp;
>> -	int pin;
>> -
>> -	pin = intel_gpio_to_pin(pctrl, irqd_to_hwirq(d), &community, &padgrp);
>> -	if (pin >= 0) {
>> -		unsigned int gpp, gpp_offset, is_offset;
>> -		unsigned long flags;
>> -		u32 value;
>> -
>> -		gpp = padgrp->reg_num;
>> -		gpp_offset = padgroup_offset(padgrp, pin);
>> -		is_offset = community->is_offset + gpp * 4;
>> -
>> -		raw_spin_lock_irqsave(&pctrl->lock, flags);
>> -		/* Clear interrupt status first to avoid unexpected interrupt */
>> -		writel(BIT(gpp_offset), community->regs + is_offset);
>> -
>> -		value = readl(community->regs + community->ie_offset + gpp * 4);
>> -		value |= BIT(gpp_offset);
>> -		writel(value, community->regs + community->ie_offset + gpp * 4);
>> -		raw_spin_unlock_irqrestore(&pctrl->lock, flags);
>> -	}
>> -}
>> -
>>  static void intel_gpio_irq_mask_unmask(struct irq_data *d, bool mask)
>>  {
>>  	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
>> @@ -963,6 +934,11 @@ static void intel_gpio_irq_mask_unmask(struct  
>> irq_data *d, bool mask)
>>  		reg = community->regs + community->ie_offset + gpp * 4;
>>
>>  		raw_spin_lock_irqsave(&pctrl->lock, flags);
>> +
>> +		/* Clear interrupt status first to avoid unexpected interrupt */
>
>> +		if (!mask)
>
> Can we do this unconditionally?

Yes I think so.

>
>> +			writel(BIT(gpp_offset), community->regs +  
>> community->is_offset + gpp * 4);
>
> I would rather prefer to follow the below pattern, like
>
> reg = ...;
> writel(..., reg);
>
> or, to decrease calculus under spin lock, something like
>
> reg = ->regs + gpp * 4;
>
> writel(..., reg + is_offset);
>
> readl(reg + ie_offset);
>
> etc.

Ok, will do.

>
>> +
>>  		value = readl(reg);
>>  		if (mask)
>>  			value &= ~BIT(gpp_offset);
>> @@ -1106,7 +1082,6 @@ static irqreturn_t intel_gpio_irq(int irq, void  
>> *data)
>>
>>  static struct irq_chip intel_gpio_irqchip = {
>>  	.name = "intel-gpio",
>
>> -	.irq_enable = intel_gpio_irq_enable,
>
> Is it possible scenario when IRQ enable is called, but not masking  
> callbacks?
> For _AEI or GPE?

I am unfamiliar with both of them, what are the callbacks to be used for  
_AEI and GPE case?
Seems like both gpiolib and irqchip call irq_unmask() when irq_enable() is  
absent.

Kai-Heng

>
>> .irq_ack = intel_gpio_irq_ack,
>>  	.irq_mask = intel_gpio_irq_mask,
>>  	.irq_unmask = intel_gpio_irq_unmask,
>
> -- 
> With Best Regards,
> Andy Shevchenko