incorporate write back support for processors not having a write through
cache.
The current fb_devconfig structure now really holds the device's
configuration and the softc really only holds the attachment information.
This used to be mixed giving rise to weird stuctures and cross references.
The number of vertical syncs before the video memory writeback is triggered
is configurable ... default is to wait for 5 Vsync .. aprox minumum 10
times a second, but more likely in the order of 12,5 times a second. When
printing is in progress no write back is performed... only after the
waiting time. The reasoning behind this is that as long as the screen is
printed too the cache will be purged of dirty data anyway due to the
processing and new screen memory useage.
on the port-acorn32's TODO list for quite some time :
- when the serial console is selected, don't exclude the screen
alltogether; currently the keyboard is still not attached but that might be
a configuration problem in the GENERIC console or a failure to explicitly
connect to a wsmux. This needs further investigation.
- create a framework for the display memory writeback on vsync for
StrongARM processors since they don't have a write-trough cache. This is to
solve the lazy screen update that is very evident in single user mode on
these processors; the cache isn't flushed/written back that often and parts
of the screen can thus be resident in the cache but not written out to
memory yet.
- clean up some loose ends in the code.
indicating an unhandled "command". ERESTART is -1, which can lead to
confusion. ERESTART has been moved to -3 and EPASSTHROUGH has been
placed at -4. No ioctl code should now return -1 anywhere. The
ioctl() system call is now properly restartable.
The IOMD/VIDC combination is now moved to arch/arm/iomd together. These
files still need a lot of cleaning up :( .... esp. the RC7500 support that
is still dormant in it; this needs either to be removed or split out for
RC7500's ``VIDC'' video/audio variant.
Apart from the RC7500 support wich is still in arch/arm32 the
iomd,vidc,riscpc and podulebus subdirectories of arch/arm32 can be removed.
This split still uses some small parts of arch/arm32 .... those are the MI
parts that haven't been moved yet.
RiscPC/A7000 have been tested and confirmed to build as should NC.
