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| 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/chips | |
| parent | ba7fbb723f50ab2607989a282af655fb0fab0492 (diff) | |
| download | linux-4b2643d7d9bdcd776749e17f73c168ddf02e93cb.tar.bz2 | |
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/chips')
| -rw-r--r-- | drivers/i2c/chips/eeprom.c | 6 | ||||
| -rw-r--r-- | drivers/i2c/chips/max6875.c | 1 |
2 files changed, 5 insertions, 2 deletions
diff --git a/drivers/i2c/chips/eeprom.c b/drivers/i2c/chips/eeprom.c index bfce13c8f1ff..48f857ae8748 100644 --- a/drivers/i2c/chips/eeprom.c +++ b/drivers/i2c/chips/eeprom.c @@ -88,8 +88,10 @@ static void eeprom_update_client(struct i2c_client *client, u8 slice) dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice); if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { - for (i = slice << 5; i < (slice + 1) << 5; i += I2C_SMBUS_BLOCK_MAX) - if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_BLOCK_MAX) + for (i = slice << 5; i < (slice + 1) << 5; i += 32) + if (i2c_smbus_read_i2c_block_data(client, i, + 32, data->data + i) + != 32) goto exit; } else { if (i2c_smbus_write_byte(client, slice << 5)) { diff --git a/drivers/i2c/chips/max6875.c b/drivers/i2c/chips/max6875.c index 76645c142977..e9e9e5171b53 100644 --- a/drivers/i2c/chips/max6875.c +++ b/drivers/i2c/chips/max6875.c @@ -106,6 +106,7 @@ static void max6875_update_slice(struct i2c_client *client, int slice) I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { if (i2c_smbus_read_i2c_block_data(client, MAX6875_CMD_BLK_READ, + SLICE_SIZE, buf) != SLICE_SIZE) { goto exit_up; } |