timeout delay in write loop too long for BD-R[E]

[Stuart R Balfour]

Binary package hint: dvd+rw-tools

dvd+rw-tools-7.1-6, kubuntu 10.04

During the course of tracking down a device buffer underrun/cache coherency
firmware problem affecting apparently only BD-R on Buffalo BRHC-6316U2
(LG GGW-H20N) firmware level XJ03, I discovered that adjusting the
timeout delay in the main write loop at ~line 515 of growisofs_mmc.cpp:

            cmd.timeout(dao_toggle?180:60);

to if (_64k)
                   cmd.timeout(dao_toggle?30:10); // reduce buffer under-runs in device cache
            else cmd.timeout(dao_toggle?180:60);

substantially reduced the extent of the buffer underruns/cache failures.
While it did not solve the problem, I think for blu-ray media, which spin
3.2 times faster base rate (1X), the delay between writes might be just too
long. I don't know what happens if we wait too little. But the host can be
suspended on signal; the media burn cannot (at least not always -
buffer underrun protection and zero-loss linking features are not yet
universal).