in connection with Marvell based SATA->PATA dongles.
The problem was caused by a combination of things working
together to make it hard to spot...
The ATA driver has always started the ATA command, then build
the SG list for DMA and then finally started the DMA engine.
While this is according to specs, it poses a potential
problem as some controllers apparently do not allow for unlimitted
time between starting the ATA command and starting the DMA engine.
At about the same time as ATAng was committed there were lots
of other changes applied, some of which was locking in parts
that causes the busdma load functions to take significantly
longer to load the SG list.
This pushed the time spent between starting the ATA command and
starting the DMA engine over the hill for some controllers
(especially the Silicon Image DS3112a) and caused what looked
like lost interrupts.
The solution is to get all the SG list work or rather all
busdma related stuff done before we even try to start anything.
This has the nice side effect of seperating busdma out the
way it should be, so the working of the ATA machinery is not
cluttered up with busdma droppings, making the code easier
to read and understand.
was that accessing the status reg could occour too fast, confusing
the logic in the flash part. Could not have been located without:
HW donated by: Jonas Bülow <jonas@servicefactory.se>
Restructure the way ATA/ATAPI commands are processed, use a common
ata_request structure for both. This centralises the way requests
are handled so locking is much easier to handle.
The driver is now layered much more cleanly to seperate the lowlevel
HW access so it can be tailored to specific controllers without touching
the upper layers. This is needed to support some of the newer
semi-intelligent ATA controllers showing up.
The top level drivers (disk, ATAPI devices) are more or less still
the same with just corrections to use the new interface.
Pull ATA out from under Gaint now that locking can be done in a sane way.
Add support for a the National Geode SC1100. Thanks to Soekris engineering
for sponsoring a Soekris 4801 to make this support.
Fixed alot of small bugs in the chipset code for various chips now
we are around in that corner anyways.
