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Date: Thu, 6 Jun 2024 14:32:38 -0700
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Kamel BOUHARA <kamel.bouhara@bootlin.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Henrik Rydberg <rydberg@bitmath.org>, linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	Marco Felsch <m.felsch@pengutronix.de>,
	Jeff LaBundy <jeff@labundy.com>,
	catalin.popescu@leica-geosystems.com,
	mark.satterthwaite@touchnetix.com,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Gregory Clement <gregory.clement@bootlin.com>,
	bsp-development.geo@leica-geosystems.com
Subject: Re: [PATCH v13 3/3] Input: Add TouchNetix axiom i2c touchscreen
 driver
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On Wed, Jun 05, 2024 at 03:48:20PM +0200, Kamel BOUHARA wrote:
> [...]
> 
> > > > +
> > > > +	error = devm_request_threaded_irq(dev, client->irq, NULL,
> > > > +					  axiom_irq, IRQF_ONESHOT, dev_name(dev), ts);
> > > > +	if (error) {
> > > > +		dev_info(dev, "Request irq failed, falling back to polling mode");
> > > 
> > > I do not think you should fall back to polling mode if you fail to get
> > > interrupt. If it was not specified (client->irq) then I can see that
> > > we
> > > might want to fall back, but if the system configured for using
> > > interrupt and you can not get it you should bail out.
> > > 
> > 
> > Yes, clear, the polling mode can be decorrelated to the irq not provided
> > case.
> 
> Just to make sure I understood, is this what you propose ?
> 
> if (client->irq) {
>         error = devm_request_threaded_irq(...)
>         if (error) {
> 		dev_warn(dev, "failed to request IRQ\n");
> 		client->irq = 0;
>          }
> }
> 
> if(!client->irq)?{
>     // setup polling stuff
>     ...
> }

No, if you fail to acquire interrupt that was described in ACPI/DT it
should be treated as an error, like this:

	if (client->irq) {
		error = devm_request_threaded_irq(...)
		if (error)
			return dev_err_probe(...);
	} else {
		.. set up polling ..
	}

This also makes sure that if interrupt controller is not ready and
requests probe deferral we will not end up with device in polling mode.

Thanks.

-- 
Dmitry