linux-kernel - Re: [PATCH RESEND 00/16] Support TI LMU devices

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Date:	Wed, 25 Nov 2015 17:51:06 +0900
From:	"Kim, Milo" <milo.kim@...com>
To:	Lee Jones <lee.jones@...aro.org>
CC:	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND 00/16] Support TI LMU devices

On 11/3/2015 5:33 PM, Lee Jones wrote:
> On Tue, 03 Nov 2015, Kim, Milo wrote:
>
>> Hi Lee,
>>
>> On 11/2/2015 5:59 PM, Lee Jones wrote:
>>>>   drivers/video/backlight/Kconfig                    |  62 ++
>>>>>   drivers/video/backlight/Makefile                   |   7 +
>>>>>   drivers/video/backlight/lm3532_bl.c                | 183 +++++
>>>>>   drivers/video/backlight/lm3631_bl.c                | 129 ++++
>>>>>   drivers/video/backlight/lm3632_bl.c                | 125 ++++
>>>>>   drivers/video/backlight/lm3633_bl.c                | 210 ++++++
>>>>>   drivers/video/backlight/lm3695_bl.c                |  91 +++
>>>>>   drivers/video/backlight/lm3697_bl.c                | 187 +++++
>>>>>   drivers/video/backlight/ti-lmu-backlight.c         | 429 ++++++++++++
>>>>>   drivers/video/backlight/ti-lmu-backlight.h         | 152 +++++
>>> How different are all of these drivers?
>>>
>>> Can you create one driver that supports them all instead?
>>>
>>
>> Thanks for your suggestion.
>>
>> 'ti-lmu-backlight' is the common part of lmxxxx_bl drivers. And each
>> lmxxx_bl has its own operation functions by using ti_lmu_bl_ops.
>> I've tried to make consolidated driver but it contained too much
>> device specific code in one file. So I prefer simple drivers
>> structure - 'common part' and 'device specific operations'.
>> It would be appreciated if you could introduce better idea.
>
> I wish to avoid having to apply the patches to conduct my own analysis
> of the files, as I am severely restricted on time.  Can you tell me how
> much duplicated code there is between the files?  How many lines would
> be saved by supporting all of the lm* drivers in a single file?
>

Now, consolidated driver is ready. It improves not only lines of code 
but also code size. Patch v2 will be sent soon.

Lines of code
-------------
194 lines are saved in consolidated driver.

Patch v1: 1420 (8 files*)
Patch v2: 1226 (3 files**)

*	ti-lmu-backlight.c (429)
	ti-lmu-backlight.h (152)
	lm3532_bl.c (183)
	lm3631_bl.c (129)
	lm3632_bl.c (125)
	lm3633_bl.c (210)
	lm3695_bl.c (95)
	lm3697_bl.c (97)

**	ti-lmu-backlight-core.c (649)
	ti-lmu-backlight-data.c (287)
	ti-lmu-backlight.h (290)

Size
----
The text segment is decreased by removing duplicate instructions.

Patch v1
    text	   data	    bss	    dec	    hex	filename
   12202	    720	     40	  12962	   32a2	drivers/video/backlight/built-in.o

Patch v2
    text	   data	    bss	    dec	    hex	filename
    6883	    712	     41	   7636	   1dd4	drivers/video/backlight/built-in.o

Test environment
----------------
- Kernel version: 4.4.0-rc2 (linux-next)
- backlight/built-in.o includes backlight core and ti-lmu-backlight 
drivers. No other backlight drivers included.

Change details will be described in the patch-set.

Best regards,
Milo
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