linux-kernel - Re: [PATCH 8/8] gpio: tqmx86: fix broken IRQ_TYPE_EDGE

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Message-ID: <9f8107e1-4a80-4f20-8862-f85aed578cc6@lunn.ch>
Date: Wed, 29 May 2024 14:37:49 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Gregor Herburger <gregor.herburger@...group.com>,
	linux@...tq-group.com
Subject: Re: [PATCH 8/8] gpio: tqmx86: fix broken IRQ_TYPE_EDGE_BOTH
 interrupt type

On Wed, May 29, 2024 at 09:45:20AM +0200, Matthias Schiffer wrote:
> The TQMx86 GPIO controller only supports falling and rising edge
> triggers, but not both. Fix this by implementing a software both-edge
> mode that toggles the edge type after every interrupt.

Do you have a real use case for this, one that will handle lost
interrupts because it cannot swap edge quick enough?

I personally would not do this, because it is dangerous, it gives the
impression the device can do both, when in fact it cannot reliably.

For me, the correct fix is to return EOPNOTSUPP or EINVAL for BOTH.

	   Andrew