linux-kernel - Re: [PATCH v2] regmap: irq: fix ack-invert

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Message-ID: <20180307143629.GG7290@sirena.org.uk>
Date:   Wed, 7 Mar 2018 14:36:29 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Tim Harvey <tharvey@...eworks.com>, linux-kernel@...r.kernel.org,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Lee Jones <lee.jones@...aro.org>, Guo Zeng <Guo.Zeng@....com>
Subject: Re: [PATCH v2] regmap: irq: fix ack-invert

On Tue, Mar 06, 2018 at 06:57:49AM -0800, Tony Lindgren wrote:

> > By using regmap_irq_update_bits to ACK the interrupts we use the masked
> > status bits so we take care not to affect any other bits then use
> > ack_invert to determine if we clear or set those bits.

> This change to use regmap_irq_update_bits() now breaks things for
> me with cpcap interrupts. So it seems to cause a non-inverted mode
> regression. There should be no need to read the ack register, I
> gues that's the whole idea of having a separate ack register :)

Yes, that'd be my expectation as well - the register should be just
write only.  regmap_update_bits() definitely isn't the right thing here
since it will suppress the write part of the read/modify/write cycle if
it detects that it didn't actually modify anything as an optimization.

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