Re: [PATCH v21 2/3] Input: mt6779-keypad - Add MediaTek keypad driver

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: AngeloGioacchino Del Regno  <angelogioacchino.delregno@collabora.com>
Cc: Mattijs Korpershoek <mkorpershoek@baylibre.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Marco Felsch <m.felsch@pengutronix.de>,
	Rob Herring <robh+dt@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Fengping Yu <fengping.yu@mediatek.com>,
	Yingjoe Chen <yingjoe.chen@mediatek.com>,
	Fabien Parent <fparent@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	linux-input@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v21 2/3] Input: mt6779-keypad - Add MediaTek keypad driver
Date: Sat, 5 Mar 2022 15:04:55 -0800	[thread overview]
Message-ID: <YiPsl41Sawjlc2E+@google.com> (raw)
In-Reply-To: <300114e2-6794-db3c-a51c-3f900b6476f9@collabora.com>

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@mediatek.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