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i2c: Fall back to emulated SMBus if the operation isn't supported natively 

Adapter drivers might support only a subset of the SMBus operations
natively. Those drivers currently have to manually emulate unsupported
operations using I2C.

Make the i2c_smbus_xfer() function fall back to
i2c_smbus_xfer_emulated() when the adapter's .smbus_xfer() operation
returns -EOPNOTSUPP, like it already does when the .smbus_xfer()
operation isn't available at all.

[JD: Minor optimization.]

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Laurent Pinchart 2012-07-24 14:13:59 +02:00 committed by Jean Delvare
parent d47726c521
commit 72fc2c7f78
1 changed files with 10 additions and 4 deletions
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14
drivers/i2c/i2c-core.c
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@ -2140,11 +2140,17 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
break;
}
i2c_unlock_adapter(adapter);
} else
res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
command, protocol, data);
return res;
if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
return res;
/*
* Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
* implement native support for the SMBus operation.
*/
}
return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
command, protocol, data);
}
EXPORT_SYMBOL(i2c_smbus_xfer);