v3: Mostly based on Ville's review comments.
- Use size_t for length all around.
- Reuse dsi_vc_send_short in dsi_vc_send_long.
- Remove stale/incorrect comments.
- Reverse special packet sent interrupt check.
- Use DSI controller regs for reading, not adapter.
Signed-off-by: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>