linux-kernel - Re: [PATCH v21 2/3] Input: mt6779-keypad

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Message-ID: <YiPsl41Sawjlc2E+@google.com>
Date:   Sat, 5 Mar 2022 15:04:55 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     Mattijs Korpershoek <mkorpershoek@...libre.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Marco Felsch <m.felsch@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Fengping Yu <fengping.yu@...iatek.com>,
        Yingjoe Chen <yingjoe.chen@...iatek.com>,
        Fabien Parent <fparent@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v21 2/3] Input: mt6779-keypad - Add MediaTek keypad driver

On Fri, Mar 04, 2022 at 11:31:38AM +0100, AngeloGioacchino Del Regno wrote:
> Il 03/03/22 16:43, Mattijs Korpershoek ha scritto:
> > From: "fengping.yu" <fengping.yu@...iatek.com>
> > +
> > +static const struct regmap_config mt6779_keypad_regmap_cfg = {
> > +	.reg_bits = 32,
> > +	.val_bits = 32,
> > +	.reg_stride = sizeof(u32),
> > +	.max_register = 36,
> 
> Are you sure that you can't use .fast_io = true?
> 
> Another version for the same question:
> Are you sure that you need to lock with a mutex here, and not with a spinlock?
> 
> Since you're performing reads over a MMIO, I think that there's a very good
> chance that you can use fast_io.

I think there are good ideas here, but they are not critical (this is a
keypad we are dealing with) and so can be investigated at a later time.

I added reporting of EV_MSC/MSC_SCAN as it is customary for
keyboard/keypad drivers, and applied the patch.

Thank you.

-- 
Dmitry