linux-kernel - Re: [PATCH v5 4/5] hwmon: add MAX197 support

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Message-ID: <20120210161538.GB1060@ericsson.com>
Date:	Fri, 10 Feb 2012 08:15:38 -0800
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
CC:	"x86@...nel.org" <x86@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	Jean Delvare <khali@...ux-fr.org>
Subject: Re: [PATCH v5 4/5] hwmon: add MAX197 support

Vivien,

On Fri, Feb 10, 2012 at 11:07:55AM -0500, Vivien Didelot wrote:
> Hi,
> 
> On Mon, 6 Feb 2012 12:46:04 -0800,
> Guenter Roeck <guenter.roeck@...csson.com> wrote:
> 
> > On Mon, 2012-02-06 at 15:15 -0500, Vivien Didelot wrote:
> > [ ... ]
> > > 
> > > BTW, about the TS-5500 ADC part, is a platform ts5500_adc.c file the
> > > better solution, or should the device be declared in the ts5500.c
> > > platform code?
> > > 
> > I would suggest to declare it in the ts5500.c platform code. That
> > seems to be the common approach as far as I can see.
> > 
> > platform_add_devices() works pretty well for this. It saves you from
> > having to call platform_device_register() for each device separately.
> > Obviously that only works if all devices are declared in a single
> > file.
> 
> As the LED is registered using the leds_class, I think
> platform_add_devices() couldn't be used here.
> 
> Lots of platform codes don't check the returned
> value of platform_add_devices(). Should we care about a LED or ADC
> registration failure (is the following snippet OK?)?
> 
>     static int __init ts5500_init(void)
>     {
>     [...]
>         pdev = platform_device_register_simple("ts5500", -1, NULL, 0); 
>         if (IS_ERR(pdev)) {
>                 ret = PTR_ERR(pdev);
>                 goto release_mem;
>         }
>         platform_set_drvdata(pdev, ts5500);
>     
>         ret = sysfs_create_group(&pdev->dev.kobj,
>                                  &ts5500_attr_group);
>         if (ret)
>                 goto release_pdev;
>     
>         led_classdev_register(&pdev->dev, &ts5500_led_cdev);
>         if (ts5500->adc) {
>                 ts5500_adc_pdev.dev.parent = &pdev->dev;
>                 platform_device_register(&ts5500_adc_pdev);
>         }
>     
I didn't look at other code, but personally I try to be consistent.
Why do you check the return value from platform_device_register_simple() above,
but not the return code from platform_device_register() ?
That does not seem to be very consistent to me.

Thanks,
Guenter

>         return 0;
>     
>         release_pdev:
>                 platform_device_unregister(pdev);
>         release_mem:
>                 kfree(ts5500);
>     
>                 return ret;
>     }
>     device_initcall(ts5500_init);
> 
> 
> Thanks,
> 
> 
> -- 
> Vivien Didelot
> Savoir-faire Linux Inc.
> Tel: (514) 276-5468 #149
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