From c680dd603857d7218b84751e9f6f0654bbfbefa2 Mon Sep 17 00:00:00 2001 From: Trent Piepho Date: Wed, 4 Apr 2007 17:11:04 -0300 Subject: V4L/DVB (5502): Sn9c102: more efficient register writing code There were many places in the driver which had long sequences of constant register initializations. These were done with one function call per register. The register address and value were immediate values in the function calls. This is very inefficient, as each register and value take twice the space when they are code, as each includes a push instruction to put it on the stack. There there is the overhead, both size and time, for a function call for each register. It's also quite a few lines of C code to do this. The patch creates a function that writes multiple registers from a list, and a macro that makes it easy to construct a such a list as a const static local to send to the function. This gets rid of quite a bit of C code, and shrinks the driver by around 8k, while at the same time being more efficient. Acked-by: Luca Risolia Signed-off-by: Trent Piepho Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/sn9c102/sn9c102_sensor.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'drivers/media/video/sn9c102/sn9c102_sensor.h') diff --git a/drivers/media/video/sn9c102/sn9c102_sensor.h b/drivers/media/video/sn9c102/sn9c102_sensor.h index 05f2942639c..1bbf64c897a 100644 --- a/drivers/media/video/sn9c102/sn9c102_sensor.h +++ b/drivers/media/video/sn9c102/sn9c102_sensor.h @@ -114,9 +114,17 @@ extern int sn9c102_i2c_write(struct sn9c102_device*, u8 address, u8 value); extern int sn9c102_i2c_read(struct sn9c102_device*, u8 address); /* I/O on registers in the bridge. Could be used by the sensor methods too */ -extern int sn9c102_write_regs(struct sn9c102_device*, u8* buff, u16 index); -extern int sn9c102_write_reg(struct sn9c102_device*, u8 value, u16 index); extern int sn9c102_pread_reg(struct sn9c102_device*, u16 index); +extern int sn9c102_write_reg(struct sn9c102_device*, u8 value, u16 index); +extern int sn9c102_write_regs(struct sn9c102_device*, const u8 valreg[][2], + int count); +/* + * Write multiple registers with constant values. For example: + * sn9c102_write_const_regs(cam, {0x00, 0x14}, {0x60, 0x17}, {0x0f, 0x18}); + */ +#define sn9c102_write_const_regs(device, data...) \ + ({ const static u8 _data[][2] = {data}; \ + sn9c102_write_regs(device, _data, ARRAY_SIZE(_data)); }) /*****************************************************************************/ -- cgit v1.2.3