linux-kernel - Re: [PATCH 3/9] irq/irq_sim: provide irq_sim_get

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Message-ID: <20190123191824.btuaq4s5rvc236n3@pengutronix.de>
Date:   Wed, 23 Jan 2019 20:18:24 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH 3/9] irq/irq_sim: provide irq_sim_get_type()

Hello Bartosz,

On Wed, Jan 23, 2019 at 03:15:32PM +0100, Bartosz Golaszewski wrote:
> Provide a helper that allows users to retrieve the configured flow type
> of dummy interrupts. That allows certain users to decide whether an irq
> needs to be fired depending on its edge/level/... configuration.

You don't talk about the .set_type callback here; is this intended?

I wonder how you think this should be used. Assume the mockup-driver is
directed to pull up a certain line, does it do something like that:

	def mockup_setval(self, val):
		irqtype = irq_sim_get_type(...)
		if irqtype == LEVEL_HIGH:
			if val:
				fire_irq()

		else if irqtype == EDGE_RISING:
			if val and not prev_val:
				fire_irq()

		else if irqtype == LEVEL_LOW:
			if not val:
				fire_irq()

		else if irqtype == EDGE_FALLING:
			if not val and prev_val:
				fire_irq()

I wonder if that logic should be done in the same place as where the irq
type is stored. Otherwise that .type member is only a data store
provided by the irq simulator. So I suggest to either move the variable
that mirrors the current level of the line into the irq simulator, or
keep the irqtype variable in the mockup driver. Both approaches would
make it unnecessary to provide an accessor function for the type member.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |