Hi all,
I am considering applying the following patch, in the hope to slightly
speed up some I2C/SMBus transfers. Am I right assuming that using memcpy
is faster than an explicit copy loop? The typical data size will be 32
bytes.
Thanks.
---
drivers/i2c/i2c-core.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
--- linux-2.6.15-git.orig/drivers/i2c/i2c-core.c 2006-01-11 18:53:43.000000000 +0100
+++ linux-2.6.15-git/drivers/i2c/i2c-core.c 2006-01-11 21:35:53.000000000 +0100
@@ -921,12 +921,11 @@
u8 length, u8 *values)
{
union i2c_smbus_data data;
- int i;
+
if (length > I2C_SMBUS_BLOCK_MAX)
length = I2C_SMBUS_BLOCK_MAX;
- for (i = 1; i <= length; i++)
- data.block[i] = values[i-1];
data.block[0] = length;
+ memcpy(data.block + 1, values, length);
return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
I2C_SMBUS_WRITE,command,
I2C_SMBUS_BLOCK_DATA,&data);
@@ -936,16 +935,14 @@
s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values)
{
union i2c_smbus_data data;
- int i;
+
if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
I2C_SMBUS_READ,command,
I2C_SMBUS_I2C_BLOCK_DATA,&data))
return -1;
- else {
- for (i = 1; i <= data.block[0]; i++)
- values[i-1] = data.block[i];
- return data.block[0];
- }
+
+ memcpy(values, data.block + 1, data.block[0]);
+ return data.block[0];
}
s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
--
Jean Delvare
-
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