diff options
| author | Jean Delvare <khali@linux-fr.org> | 2007-07-12 14:12:29 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@hyperion.delvare> | 2007-07-12 14:12:29 +0200 |
| commit | 4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch) | |
| tree | 1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/busses/scx200_acb.c | |
| parent | ba7fbb723f50ab2607989a282af655fb0fab0492 (diff) | |
i2c: Fix the i2c_smbus_read_i2c_block_data() prototype
Let the drivers specify how many bytes they want to read with
i2c_smbus_read_i2c_block_data(). So far, the block count was
hard-coded to I2C_SMBUS_BLOCK_MAX (32), which did not make much sense.
Many driver authors complained about this before, and I believe it's
about time to fix it. Right now, authors have to do technically stupid
things, such as individual byte reads or full-fledged I2C messaging,
to work around the problem. We do not want to encourage that.
I even found that some bus drivers (e.g. i2c-amd8111) already
implemented I2C block read the "right" way, that is, they didn't
follow the old, broken standard. The fact that it was never noticed
before just shows how little i2c_smbus_read_i2c_block_data() was used,
which isn't that surprising given how broken its prototype was so far.
There are some obvious compatiblity considerations:
* This changes the i2c_smbus_read_i2c_block_data() prototype. Users
outside the kernel tree will notice at compilation time, and will
have to update their code.
* User-space has access to i2c_smbus_xfer() directly using i2c-dev, so
the changed expectations would affect tools such as i2cdump. In order
to preserve binary compatibility, we give I2C_SMBUS_I2C_BLOCK_DATA
a new numeric value, and define I2C_SMBUS_I2C_BLOCK_BROKEN with the
old numeric value. When i2c-dev receives a transaction with the
old value, it can convert it to the new format on the fly.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c/busses/scx200_acb.c')
| -rw-r--r-- | drivers/i2c/busses/scx200_acb.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/i2c/busses/scx200_acb.c b/drivers/i2c/busses/scx200_acb.c index dc64f8b6b24..e6c4a2b762e 100644 --- a/drivers/i2c/busses/scx200_acb.c +++ b/drivers/i2c/busses/scx200_acb.c @@ -310,8 +310,6 @@ static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter, break; case I2C_SMBUS_I2C_BLOCK_DATA: - if (rw == I2C_SMBUS_READ) - data->block[0] = I2C_SMBUS_BLOCK_MAX; /* For now */ len = data->block[0]; if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) return -EINVAL; |