Hi Daniel,
> The i2c bus requires 4 bytes to do a 1-byte write
> (1 byte i2c address + 2 byte offset + 1 byte data).
>
> By taking a length with writes, the driver can amortize transaction
> overhead by performing larger transactions where appropriate.
>
> This patch just sets up the new API. Later patches refactor writes
> to take advantage of the larger transactions.
>
> Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 22 +++++++++++++++++-----
> 1 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 3672553..d9e7e68 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -431,17 +431,24 @@ static int mxt_read_reg(struct i2c_client *client, u16 reg, u8 *val)
> return __mxt_read_reg(client, reg, 1, val);
> }
>
> -static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
> +static int __mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
> + const void *val)
> {
> - u8 buf[3];
> + u8 *buf;
> + size_t count;
> int ret;
>
> + count = len + 2;
> + buf = kmalloc(count, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> buf[0] = reg & 0xff;
> buf[1] = (reg >> 8) & 0xff;
> - buf[2] = val;
> + memcpy(&buf[2], val, len);
>
> - ret = i2c_master_send(client, buf, 3);
> - if (ret == 3) {
> + ret = i2c_master_send(client, buf, count);
> + if (ret == count) {
> ret = 0;
> } else {
> if (ret >= 0)
> @@ -453,6 +460,11 @@ static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
kfree(buf);
> return ret;
> }
>
> +static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
> +{
> + return __mxt_write_reg(client, reg, 1, &val);
> +}
> +
> static int mxt_read_object_table(struct i2c_client *client,
> u16 reg, u8 *object_buf)
> {
> --
> 1.7.7.3
>
Thanks,
Henrik
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
