linux-kernel - Re: [PATCH 0/3] Migrate PCIe-IDIO-24 GPIO driver to the regmap API

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Date:   Tue, 28 Feb 2023 19:28:45 +0000
From:   Mark Brown <broonie@...nel.org>
To:     William Breathitt Gray <william.gray@...aro.org>
Cc:     linus.walleij@...aro.org, brgl@...ev.pl,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        michael@...le.cc, quarium@...il.com, jhentges@...esio.com,
        jay.dolan@...esio.com
Subject: Re: [PATCH 0/3] Migrate PCIe-IDIO-24 GPIO driver to the regmap API

On Mon, Feb 27, 2023 at 09:19:28PM -0500, William Breathitt Gray wrote:
> On Tue, Feb 28, 2023 at 07:09:50PM +0000, Mark Brown wrote:

> > The values from the config buffer are supposed to be written out in
> > regmap_irq_sync_unlock() - why is something custom needed here?

> The PCIe-IDIO-24 "COS Enable" serves a dual purpose of interrupt
> enabling/disabling as well as configuring the interrupt types. Since
> this register is used for masking, config buffer would clobber the
> register if we use it in this particular case. Instead, we ignore the
> config buffer and configure the type directly for the device (handling
> the case where interrupts are masked and shouldn't be enabled).

Could you be more concrete about what's going on here please?  In what
way does this "COS Enable" serve these dual functions and why do they
clobber each other?

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