linux-kernel - Re: [PATCH v4 06/10] regmap: irq: Add support for chips without separate IRQ status

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Message-Id: <D7SADDQZUERA.PT8QLVZ9ZN1N@bootlin.com>
Date: Fri, 14 Feb 2025 16:49:57 +0100
From: "Mathieu Dubois-Briand" <mathieu.dubois-briand@...tlin.com>
To: "Andy Shevchenko" <andriy.shevchenko@...el.com>
Cc: "Lee Jones" <lee@...nel.org>, "Rob Herring" <robh@...nel.org>,
 "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor Dooley"
 <conor+dt@...nel.org>, "Kamel Bouhara" <kamel.bouhara@...tlin.com>, "Linus
 Walleij" <linus.walleij@...aro.org>, "Bartosz Golaszewski" <brgl@...ev.pl>,
 "Dmitry Torokhov" <dmitry.torokhov@...il.com>,
 Uwe Kleine-König <ukleinek@...nel.org>, "Michael Walle"
 <mwalle@...nel.org>, "Mark Brown" <broonie@...nel.org>, "Greg
 Kroah-Hartman" <gregkh@...uxfoundation.org>, "Rafael J. Wysocki"
 <rafael@...nel.org>, "Danilo Krummrich" <dakr@...nel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-gpio@...r.kernel.org>, <linux-input@...r.kernel.org>,
 <linux-pwm@...r.kernel.org>, Grégory Clement
 <gregory.clement@...tlin.com>, "Thomas Petazzoni"
 <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 06/10] regmap: irq: Add support for chips without
 separate IRQ status

On Fri Feb 14, 2025 at 4:18 PM CET, Andy Shevchenko wrote:
> On Fri, Feb 14, 2025 at 12:49:56PM +0100, Mathieu Dubois-Briand wrote:
> > Some GPIO chips allow to rise an IRQ on GPIO level changes but do not
> > provide an IRQ status for each separate line: only the current gpio
> > level can be retrieved.
> > 
> > Add support for these chips, emulating IRQ status by comparing GPIO
> > levels with the levels during the previous interrupt.
>
> Thanks, this will help to convert more drivers to regmap
> (e.g., gpio-pca953x that seems use similar approach).
>
> ...
>
> > +static irqreturn_t regmap_irq_thread(int irq, void *d)
> > +{
> > +	struct regmap_irq_chip_data *data = d;
> > +	const struct regmap_irq_chip *chip = data->chip;
> > +	struct regmap *map = data->map;
> > +	int ret, i;
>
> 	unsigned int i;
> ?

I agree, but signed int index variables are used in all functions of
this file. What would be the best approach here? Only fix it on code
parts I modified? On the whole file?

>
> > +	bool handled = false;
> > +	u32 reg;
> > +
> > +	if (chip->handle_pre_irq)
> > +		chip->handle_pre_irq(chip->irq_drv_data);
> > +
> > +	if (chip->runtime_pm) {
> > +		ret = pm_runtime_get_sync(map->dev);
> > +		if (ret < 0) {
>
> > +			dev_err(map->dev, "IRQ thread failed to resume: %d\n",
> > +				ret);
>
> Can be one line.
>

Yes. Kind of the same question here: should I fix only the code close to
the parts I modified or the whole file?

> ...
>
> > +		for (i = 0; i < d->chip->num_regs; i++)
> > +			d->prev_status_buf[i] = d->status_buf[i];
>
> Hmm... Wouldn't memcpy() suffice?
> But okay, this seems to be not a hot path and the intention is clear.

Yes... I don't know why I didn't use memcpy. I will fix it.

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com