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List:       mjpeg-users
Subject:    [Mjpeg-users] [PATCH 7/7] bt856: Shrink register cache
From:       Jean Delvare <khali () linux-fr ! org>
Date:       2006-01-08 16:12:05
Message-ID: 20060108171205.03c37149.khali () linux-fr ! org
[Download RAW message or body]

The bt856 driver has a register cache much larger than needed. We
really only write to 3 registers, so a 32-byte cache is a bit too
much. We can be just as efficient with a 6-byte cache. We could even
do with a 3-byte cache, but at the cost of additional arithmetics
arguably not worth the spared 3 bytes.

Also, 4 of the 6 other members of the bt856 data structure were not
used anywhere, so we can as well drop them for an additional 16 bytes
of memory spared.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/media/video/bt856.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

--- linux-2.6.15-git.orig/drivers/media/video/bt856.c	2006-01-08 12:09:17.000000000 +0100
+++ linux-2.6.15-git/drivers/media/video/bt856.c	2006-01-08 15:25:11.000000000 +0100
@@ -71,17 +71,14 @@
 
 /* ----------------------------------------------------------------------- */
 
-#define REG_OFFSET  0xCE
+#define REG_OFFSET	0xDA
+#define BT856_NR_REG	6
 
 struct bt856 {
-	unsigned char reg[32];
+	unsigned char reg[BT856_NR_REG];
 
 	int norm;
 	int enable;
-	int bright;
-	int contrast;
-	int hue;
-	int sat;
 };
 
 #define   I2C_BT856        0x88
@@ -120,8 +117,8 @@
 	struct bt856 *encoder = i2c_get_clientdata(client);
 
 	printk(KERN_INFO "%s: register dump:", I2C_NAME(client));
-	for (i = 0xd6; i <= 0xde; i += 2)
-		printk(" %02x", encoder->reg[i - REG_OFFSET]);
+	for (i = 0; i < BT856_NR_REG; i += 2)
+		printk(" %02x", encoder->reg[i]);
 	printk("\n");
 }
 

-- 
Jean Delvare


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