Documentation: i2c: slave: describe buffer problems a bit better

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/Documentation/i2c/slave-interface b/Documentation/i2c/slave-interface
index 61ed05c..abd1018 100644
--- a/Documentation/i2c/slave-interface
+++ b/Documentation/i2c/slave-interface
@@ -173,13 +173,14 @@
 bytes came up. Such an extension might be possible, usefulness is unclear at
 this time of writing. Some points to keep in mind when using buffers:
 
-* Buffers should be opt-in and slave drivers will always have to support
-  byte-based transactions as the ultimate fallback because this is how the
-  majority of HW works.
+* Buffers should be opt-in and backend drivers will always have to support
+  byte-based transactions as the ultimate fallback anyhow because this is how
+  the majority of HW works.
 
-* For backends simulating hardware registers, buffers are not helpful because
-  on writes an action should be immediately triggered. For reads, the data in
-  the buffer might get stale.
+* For backends simulating hardware registers, buffers are largely not helpful
+  because after each byte written an action should be immediately triggered.
+  For reads, the data kept in the buffer might get stale if the backend just
+  updated a register because of internal processing.
 
 * A master can send STOP at any time. For partially transferred buffers, this
   means additional code to handle this exception. Such code tends to be