linux-kernel - Re: sisusb: Use static const, fix typo

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Date:	Mon, 24 Feb 2014 10:01:16 -0800
From:	Joe Perches <joe@...ches.com>
To:	David Laight <David.Laight@...LAB.COM>
Cc:	Thomas Winischhofer <thomas@...ischhofer.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb <linux-usb@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: sisusb: Use static const, fix typo

On Mon, 2014-02-24 at 10:26 +0000, David Laight wrote:
> From: Joe Perches
> > Reduce text a bit by using static const.
> 
> If you want to save a few bytes remove the pointers.
> (and the fixed RAM text to get below 7 chars).

Hi David.

> eg:
> 
> > -	const char *ramtypetext2[] = {	"SDR SDRAM", "SDR SGRAM",
> > -					"DDR SDRAM", "DDR SGRAM" };

The idea was use static to avoid the array reload
on each function entry.

> 	static const char ramtypetext2[8][] = {
> 		"SDR SD", "SDR SG", "DDR SD", "DDR SG"

8 is an odd number here.

That could be done with char like:

	static const char ram_datarate[4] = {'S', 'S', 'D', 'D'};
	static const char ram_dynamictype[4] = {'D', 'G', 'D', 'G'};
> ...
> > -	dev_info(&sisusb->sisusb_dev->dev, "%dMB %s %s, bus width %d\n", (sisusb->vramsize >> 20),
> > ramtypetext1,
> > -			ramtypetext2[ramtype], bw);
> 
> 	dev_info(&sisusb->sisusb_dev->dev, "%dMB %s %sRAM, bus width %d\n",
> 		 sisusb->vramsize >> 20, ramtypetext1, ramtypetext2[ramtype],
> 		 bw);

	dev_info(&sisusb->sisusb_dev->dev, "%dMB %s %c%cRAM, bus width %d\n",
		 sisusb->vramsize >> 20, ramtypetext1,
		 ram_datarate[ramtype], ram_dynamictype[ramtype], bw);

So something like:

Convert 1 char * array to 2 char arrays to reduce size.
Use static const to avoid array reloads on function entry.
Fix asymmetric typo.

$ size drivers/usb/misc/sisusbvga/sisusb.o*
   text	   data	    bss	    dec	    hex	filename
  29971	   4841	   9180	  43992	   abd8	drivers/usb/misc/sisusbvga/sisusb.o.new
  30083	   4841	   9180	  44104	   ac48	drivers/usb/misc/sisusbvga/sisusb.o.old

Signed-off-by: Joe Perches <joe@...ches.com>
---
 drivers/usb/misc/sisusbvga/sisusb.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c
index de98906..06b5d77 100644
--- a/drivers/usb/misc/sisusbvga/sisusb.c
+++ b/drivers/usb/misc/sisusbvga/sisusb.c
@@ -2123,8 +2123,8 @@ sisusb_get_ramconfig(struct sisusb_usb_data *sisusb)
 	u8 tmp8, tmp82, ramtype;
 	int bw = 0;
 	char *ramtypetext1 = NULL;
-	const char *ramtypetext2[] = {	"SDR SDRAM", "SDR SGRAM",
-					"DDR SDRAM", "DDR SGRAM" };
+	static const char ram_datarate[4] = {'S', 'S', 'D', 'D'};
+	static const char ram_dynamictype[4] = {'D', 'G', 'D', 'G'};
 	static const int busSDR[4]  = {64, 64, 128, 128};
 	static const int busDDR[4]  = {32, 32,  64,  64};
 	static const int busDDRA[4] = {64+32, 64+32 , (64+32)*2, (64+32)*2};
@@ -2156,8 +2156,10 @@ sisusb_get_ramconfig(struct sisusb_usb_data *sisusb)
 		break;
 	}
 
-	dev_info(&sisusb->sisusb_dev->dev, "%dMB %s %s, bus width %d\n", (sisusb->vramsize >> 20), ramtypetext1,
-			ramtypetext2[ramtype], bw);
+
+	dev_info(&sisusb->sisusb_dev->dev, "%dMB %s %cDR S%cRAM, bus width %d\n",
+		 sisusb->vramsize >> 20, ramtypetext1,
+		 ram_datarate[ramtype], ram_dynamictype[ramtype], bw);
 }
 
 static int


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