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

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Date:   Fri, 4 Mar 2022 14:38:14 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     Mattijs Korpershoek <mkorpershoek@...libre.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.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>
> > 
> > This patch adds matrix keypad support for Mediatek SoCs.

> > +struct mt6779_keypad {
> > +	struct regmap *regmap;
> > +	struct input_dev *input_dev;
> > +	struct clk *clk;

> > +	void __iomem *base;

Not sure why you need this here.

> > +	u32 n_rows;
> > +	u32 n_cols;
> > +	DECLARE_BITMAP(keymap_state, MTK_KPD_NUM_BITS);
> > +};
> > +
> > +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.
> 
> > +};

...

> Please use dev_err_probe() to simplify error handling in probe functions: you've
> done a great job with adding a devm action for the error cases, avoiding gotos to
> get out cleanly.. it would be a pity to not finish this to perfection.
> 
> I'll give you two examples for this, so that you'll be all set.
> 
> 	if (IS_ERR(keypad->regmap))
> 		return dev_err_probe(&pdev->dev, PTR_ERR(keypad->regmap),
> 				     "regmap init failed\n");
> 
> P.S.: No need for %pe here, as dev_err_probe prints the error number for you!

Maintainer of the input subsystem is strongly against dev_err_probe() API. See
other files there. Ditto for other cases you mentioned below.

-- 
With Best Regards,
Andy Shevchenko