sed inside the sequencer without passing to
the lowlevel driver.
<H4>
7.2.3 Load_Patch Callback</H4>
The <TT>load_patch</TT> callback is used for sample-downloading. This callback
must read the data on user-space and transfer to each device. Return 0
if succeeded, and -errno if failed. The format argument is the patch key
in patch_info record. The buf is user-space pointer where patch_info record
is stored. The offs can be ignored. The count is total data size of this
sample data.
<H4>
7.2.4 Close Callback<