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authorJean Delvare <khali@linux-fr.org>2007-07-12 08:12:29 -0400
committerJean Delvare <khali@hyperion.delvare>2007-07-12 08:12:29 -0400
commit4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch)
tree1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/busses/i2c-powermac.c
parentba7fbb723f50ab2607989a282af655fb0fab0492 (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/i2c-powermac.c')
-rw-r--r--drivers/i2c/busses/i2c-powermac.c3
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,
121 if (rc) 121 if (rc)
122 goto bail; 122 goto bail;
123 rc = pmac_i2c_xfer(bus, addrdir, 1, command, 123 rc = pmac_i2c_xfer(bus, addrdir, 1, command,
124 read ? data->block : &data->block[1], 124 &data->block[1], data->block[0]);
125 data->block[0]);
126 break; 125 break;
127 126
128 default: 127 default: