1. We record host (write) buffer depth during reset so we don't need to query HCSR register later on. The host buffer depth doesn't change after the reset 2. Use mei_hbuf_max_data function to compute payload size in bytes Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>