* At least some nVidia HDA controllers do not acknowledge the CORB
read pointer reset, which is required by the spec (cf. HDA 1.0a
ch. 3.3.21). For these controllers, do not fail when acknowledge
is missing.
* Makes hda driver work for nVidia HDA controllers again, thus fixing
the regression pointed out in #10212.
* Some chipsets do not support bus-snooping for the HDA data
transfers. So, when trying to enable snooping, verify that the
setting was accepted.
* When snooping is not possible, set memory areas for audio buffers,
buffer descriptor lists and command ring-buffers as uncached to
ensure memory coherency with the HDA controller.
* This fixes KDLs during booting on some systems where snooping
is not supported (seen on two systems with AMD chipsets, maybe
applies to others as well).
After setting up the buffer descriptor list for a stream, it was a
gamble whether these writes would be visible to the HDA controller
when subsequently enabling the stream. On some boots it was unlucky
and then the HDA controller's DMA engine would go haywire and start
overwriting random kernel memory with audio input data. The
scheduler was usually the first victim and caused page fault KDLs
due to corrupted data structures.
* Do read-modify-write cycle to preserve bits marked as RsvdP in the
following registers: WAKEEN, CORBWP, CORBCTL, CORBSIZE, RIRBWP,
RINTCNT, RIRBCTL, RIRBSIZE.
* Spec requires software to wait for hardware to acknowledge the
reset by waiting for the bit to become set and then manually
unset it and again wait for it to become unset.
(cf. HDA spec 1.0a ch. 3.3.21)
* Also, do read-modify-write to protect preserved bits
As the keyboard is used from usb_hid in the userland as well, we quite
probably are not in sync with the data toggle. Clearing the stall
should restore the toggle and make things work.
It constructs a clear feature request for the endpoint halt selector
and sends the request using debug transfers. Clearing a stall condition
can be done safely and has one nice side effect: it reinitializes the
data toggle to a known state. This command can therefore be used when
a pipe is possibly used from userland as well and the data toggle may
therefore be out of sync.
Pull debug transfer methods into the base BusManager class and
implement them for UHCI and EHCI. This makes it possible to have a
single debugger command installed by the USB stack instead of HCI
specific ones.
The alternate pointer is the software equivalent of the alternate
physical address in the hardware queue head part. The controller
follows that path, so we can follow the alternate pointer as well.
Simplifies and generalizes the logic.
Since it's possible to fail queuing them, the count doesn't go down to 0,
and the process just hangs forever on exit. It might not be necessary anyway.
