and XMITS has to be basically done in the same manner as for
the Sabres, i.e. only for devices behind PCI-PCI-bridges and
after a PIO read on the far side of the farest PCI-PCI-bridge.
Given that the Tomatillo documentation mentions no difference
to the Schizo bridges in this regard and this is also still
part of the procedure described Schizo documentation this
seems about right so adjust accordingly (the unconditional
CDMA flushing/syncing previously done was based on how Linux
behaves).
- Implement CDMA flushing/syncing for Schizo version >= 5,
which requires the workaround described in Schizo Errata I-23.
According to Schizo Errata I-13 it's just unusable with
version < 5 though. [1]
- Don't register the Schizo streaming buffer for now until it's
usage is sorted out according to the erratas.
- Register our interrupt filters with the revived INTR_FAST so
they these interrupts can even interrupt filters of device
drivers as necessary.
- Remove the comment regarding lack of newbus'ified bus_dma(9)
as being able to associate a DMA tag with a device would
allow to implement CDMA flushing/syncing in bus_dmamap_sync(9)
but that would totally kill performance. Given that for devices
not behind a PCI-PCI bridge the host-to-PCI bridges also only
do CDMA flushing/syncing based on interrupts there's no
additional disadvantage for polling(4) callbacks in the case
schizo(4) has to do the CDMA flushing/syncing but rather a
general problem.
Reported by: Michael Moll [1]
JBus to PCI 2.2 bridges. In theory, this driver should also handle
`XMITS' Fireplane/Safari to PCI-X bridges but due to lack of access
to such hardware, support for these hasn't be fleshed out, yet.
