linux-kernel - Re: [PATCH] ACPI : Dummy acpi_video_register should return error code

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Message-ID: <aad366c0-7531-6820-f378-84020ceb45fc@intel.com>
Date:	Thu, 23 Jun 2016 09:35:01 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Arvind Yadav <arvind.yadav.cs@...il.com>
Cc:	robert.moore@...el.com, lv.zheng@...el.com,
	rafael.j.wysocki@...el.com, lenb@...nel.org,
	linux-acpi@...r.kernel.org, devel@...ica.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI : Dummy acpi_video_register should return error code

On 06/23/2016 05:05 AM, Rafael J. Wysocki wrote:
> On Thursday, June 23, 2016 12:26:01 AM Arvind Yadav wrote:
>> The inline acpi_video_register stub simply allows compilation on systems
>> with CONFIG_ACPI_VIDEO disabled. the dummy acpi_video_register does not
>> register an acpi_bus_driver at all. The inline acpi_video_register should
>> return to indicate lack of support when attempting to register an
>> acpi_bus_driver on such a system with CONFIG_ACPI_VIDEO disabled.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>>  include/acpi/video.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/acpi/video.h b/include/acpi/video.h
>> index 5731ccb..4536bd3 100644
>> --- a/include/acpi/video.h
>> +++ b/include/acpi/video.h
>> @@ -54,7 +54,7 @@ extern int acpi_video_get_levels(struct acpi_device *device,
>>  				 struct acpi_video_device_brightness **dev_br,
>>  				 int *pmax_level);
>>  #else
>> -static inline int acpi_video_register(void) { return 0; }
>> +static inline int acpi_video_register(void) { return -ENODEV; }
>>  static inline void acpi_video_unregister(void) { return; }
>>  static inline int acpi_video_get_edid(struct acpi_device *device, int type,
>>  				      int device_id, void **edid)
> 
> Aaron, what do you think?
 
The only place that cares about the return value of acpi_video_register
is in acpi_video_init where CONFIG_ACPI_VIDEO must be defined, all other
places do not care about the return value so this change shouldn't cause
any problems and returning -ENODEV sounds more reasonable than 0 here.

Reviewed-by: Aaron Lu <aaron.lu@...el.com>

Regards,
Aaron