Re: [PATCH 2/4] input: keyboard/mouse/touchscreen/misc: Use dev_get_drvdata()

From: Lee Jones <lee.jones@linaro•org>
To: "Lothar Waßmann" <LW@KARO-electronics•de>
Cc: Kate Stewart <kstewart@linuxfoundation•org>,
	Tony Lindgren <tony@atomide•com>,
	Richard Fontana <rfontana@redhat•com>,
	Laxman Dewangan <ldewangan@nvidia•com>,
	Fabio Estevam <festevam@gmail•com>, Rob Herring <robh@kernel•org>,
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	Anson Huang <anson.huang@nxp•com>,
	Jonathan Hunter <jonathanh@nvidia•com>,
	Luca Weiss <luca@z3ntu•xyz>,
	Andy Shevchenko <andy.shevchenko@gmail•com>,
	NXP Linux Team <linux-imx@nxp•com>,
	linux-input <linux-input@vger•kernel.org>,
	Fuqian Huang <huangfq.daxian@gmail•com>,
	Dan Carpenter <dan.carpenter@oracle•com>,
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	Gabriel Fernandez <gabriel.fernandez@st•com>
Subject: Re: [PATCH 2/4] input: keyboard/mouse/touchscreen/misc: Use dev_get_drvdata()
Date: Wed, 3 Jul 2019 07:17:46 +0100	[thread overview]
Message-ID: <20190703061746.GI4652@dell> (raw)
In-Reply-To: <20190702143225.12b0fe07@karo-electronics.de>

On Tue, 02 Jul 2019, Lothar Waßmann wrote:

> Hi,
> 
> On Tue, 2 Jul 2019 19:47:16 +0800 Fuqian Huang wrote:
> > Andy Shevchenko <andy.shevchenko@gmail•com> 於 2019年7月2日週二 下午5:51寫道：
> > >
> > > On Tue, Jul 2, 2019 at 11:20 AM Fuqian Huang <huangfq.daxian@gmail•com> wrote:  
> > > >
> > > > I am not an expert on this. I just write a coccinelle script to search
> > > > this kind of misuse and fix it in a naive way.
> > > > Could you tell me about how to use the proper bus accessors? Then I
> > > > will fix it up and resend a v2 patch set.  
> > >
> > > First, don't top post.
> > > And answering to this, simple drop the patch.
> > > Proper bus accessors is exactly what it's used in the current code.  
> > 
> > But why not use dev_get_drvdata directly.
> > It simplifies getting the 'driver_data' from 'struct device' directly.
> > And the platform_device here is not required.
> > Replace it can remove the unnecessary step back and forth. (dev -> pdev -> dev).
> > 
> Did you check whether the compiler generates different (better) code
> with and without your patch? My guess is it won't.

I can see Fuqian's point.  If bus APIs are preferred, maybe it would
be nicer if the function was adapted to accept a platform_device
instead?

Caveat: I haven't taken the time to look into the call-site details.
	This comment is based on just the patch alone.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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