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i2c: Fix the i2c_smbus_read_i2c_block_data() prototype

Telusuri Sumber 
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>
This commit is contained in:
Jean Delvare
2007-07-12 14:12:29 +02:00
committed by Jean Delvare
orang tua ba7fbb723f
melakukan 4b2643d7d9
11 mengubah file dengan 32 tambahan dan 40 penghapusan
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28
drivers/macintosh/windfarm_smu_sat.c
Melihat File

@@ -67,26 +67,6 @@ static struct i2c_driver wf_sat_driver = {
.detach_client = wf_sat_detach,
};
/*
* XXX i2c_smbus_read_i2c_block_data doesn't pass the requested
* length down to the low-level driver, so we use this, which
* works well enough with the SMU i2c driver code...
*/
static int sat_read_block(struct i2c_client *client, u8 command,
u8 *values, int len)
{
union i2c_smbus_data data;
int err;
data.block[0] = len;
err = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
I2C_SMBUS_READ, command, I2C_SMBUS_I2C_BLOCK_DATA,
&data);
if (!err)
memcpy(values, data.block, len);
return err;
}
struct smu_sdbp_header *smu_sat_get_sdb_partition(unsigned int sat_id, int id,
unsigned int *size)
{
@@ -124,8 +104,8 @@ struct smu_sdbp_header *smu_sat_get_sdb_partition(unsigned int sat_id, int id,
return NULL;
for (i = 0; i < len; i += 4) {
err = sat_read_block(&sat->i2c, 0xa, data, 4);
if (err) {
err = i2c_smbus_read_i2c_block_data(&sat->i2c, 0xa, 4, data);
if (err < 0) {
printk(KERN_ERR "smu_sat_get_sdb_part rd err %d\n",
err);
goto fail;
@@ -157,8 +137,8 @@ static int wf_sat_read_cache(struct wf_sat *sat)
{
int err;
err = sat_read_block(&sat->i2c, 0x3f, sat->cache, 16);
if (err)
err = i2c_smbus_read_i2c_block_data(&sat->i2c, 0x3f, 16, sat->cache);
if (err < 0)
return err;
sat->last_read = jiffies;
#ifdef LOTSA_DEBUG