linux-kernel - Re: [PATCH RFC] video: fbdev: sis: condition with no effect

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Message-ID: <alpine.LNX.2.11.1502052013430.700@localhost>
Date:	Thu, 5 Feb 2015 20:45:59 +0000 (UTC)
From:	Scot Doyle <lkml14@...tdoyle.com>
To:	Nicholas Mc Guire <hofrat@...dl.org>
cc:	Thomas Winischhofer <thomas@...ischhofer.net>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] video: fbdev: sis: condition with no effect

On Wed, 4 Feb 2015, Nicholas Mc Guire wrote:
> The if and the else branch code are identical - so the condition has no
> effect on the effective code - this patch removes the condition and the
> duplicated code.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
> 
> This code has been in here since commit 544393fe584d ("sisfb update") so I guess it is
> safe to simply remove the duplicated code if nobody noticed for 10 years.
> 
> Note that the code is not really CodingStyle compliant - the lines inserted were formatted
> to satisfy the coding style but I'm unsure if it is not better to leave it in the
> old format.
> 
> Patch was only compile tested with x86_64_defconfig +
> CONFIG_FB_SIS=m, CONFIG_FB_SIS_300=y, CONFIG_FB_SIS_315=y
> 
> Patch is against 3.19.0-rc7 (localversion-next is -next-20150204)
> 
>  drivers/video/fbdev/sis/init301.c |    9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/video/fbdev/sis/init301.c b/drivers/video/fbdev/sis/init301.c
> index 295e0de..9533a8ab 100644
> --- a/drivers/video/fbdev/sis/init301.c
> +++ b/drivers/video/fbdev/sis/init301.c
> @@ -7971,13 +7971,8 @@ SiS_SetCHTVReg(struct SiS_Private *SiS_Pr, unsigned short ModeNo, unsigned short
>           }
>        } else {						/* ---- PAL ---- */
>           /* We don't play around with FSCI in PAL mode */
> -         if(resindex == 0x04) {
> -            SiS_SetCH70xxANDOR(SiS_Pr,0x20,0x00,0xEF);	/* loop filter off */
> -            SiS_SetCH70xxANDOR(SiS_Pr,0x21,0x01,0xFE);	/* ACIV on */
> -         } else {
> -            SiS_SetCH70xxANDOR(SiS_Pr,0x20,0x00,0xEF);	/* loop filter off */
> -            SiS_SetCH70xxANDOR(SiS_Pr,0x21,0x01,0xFE);	/* ACIV on */
> -         }
> +	  SiS_SetCH70xxANDOR(SiS_Pr, 0x20, 0x00, 0xEF);	/* loop filter off */
> +	  SiS_SetCH70xxANDOR(SiS_Pr, 0x21, 0x01, 0xFE);	/* ACIV on */
>        }
>  
>  #endif  /* 300 */

The code covering the PAL case had this redundancy when it was introduced 
in Linux 2.4.19.

Lines 7934-7981 consider three variables: PAL, overscan, and resindex. 
Given the "#ifdef 0" block, couldn't the current six sections collapse 
into two? One for (!PAL && overscan && resindex==5) and another for the 
rest?
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