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>
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 361978a..26488aa 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -2140,11 +2140,17 @@
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);