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| author | Jean Delvare <khali@linux-fr.org> | 2007-07-12 16:12:29 +0400 |
|---|---|---|
| committer | Jean Delvare <khali@hyperion.delvare> | 2007-07-12 16:12:29 +0400 |
| commit | 4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch) | |
| tree | 1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/busses/i2c-powermac.c | |
| parent | ba7fbb723f50ab2607989a282af655fb0fab0492 (diff) | |
| download | linux-4b2643d7d9bdcd776749e17f73c168ddf02e93cb.tar.xz | |
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/i2c-powermac.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-powermac.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-powermac.c b/drivers/i2c/busses/i2c-powermac.c index 1425d2245c82..0ab4f2627c26 100644 --- a/drivers/i2c/busses/i2c-powermac.c +++ b/drivers/i2c/busses/i2c-powermac.c @@ -121,8 +121,7 @@ static s32 i2c_powermac_smbus_xfer( struct i2c_adapter* adap, if (rc) goto bail; rc = pmac_i2c_xfer(bus, addrdir, 1, command, - read ? data->block : &data->block[1], - data->block[0]); + &data->block[1], data->block[0]); break; default: |