This introduces support for CRC readback on gf119+, using the
documentation generously provided to us by Nvidia:
https://github.com/NVIDIA/open-gpu-doc/blob/master/Display-CRC/display-crc.txt
We expose all available CRC sources. SF, SOR, PIOR, and DAC are exposed
through a single set of "outp" sources: outp-active/auto for a CRC of
the scanout region, outp-complete for a CRC of both the scanout and
blanking/sync region combined, and outp-inactive for a CRC of only the
blanking/sync region. For each source, nouveau selects the appropriate
tap point based on the output path in use. We also expose an "rg"
source, which allows for capturing CRCs of the scanout raster before
it's encoded into a video signal in the output path. This tap point is
referred to as the raster generator.
Note that while there's some other neat features that can be used with
CRC capture on nvidia hardware, like capturing from two CRC sources
simultaneously, I couldn't see any usecase for them and did not
implement them.
Nvidia only allows for accessing CRCs through a shared DMA region that
we program through the core EVO/NvDisplay channel which is referred to
as the notifier context. The notifier context is limited to either 255
(for Fermi-Pascal) or 2047 (Volta+) entries to store CRCs in, and
unfortunately the hardware simply drops CRCs and reports an overflow
once all available entries in the notifier context are filled.
Since the DRM CRC API and igt-gpu-tools don't expect there to be a limit
on how many CRCs can be captured, we work around this in nouveau by
allocating two separate notifier contexts for each head instead of one.
We schedule a vblank worker ahead of time so that once we start getting
close to filling up all of the available entries in the notifier
context, we can swap the currently used notifier context out with
another pre-prepared notifier context in a manner similar to page
flipping.
Unfortunately, the hardware only allows us to this by flushing two
separate updates on the core channel: one to release the current
notifier context handle, and one to program the next notifier context's
handle. When the hardware processes the first update, the CRC for the
current frame is lost. However, the second update can be flushed
immediately without waiting for the first to complete so that CRC
generation resumes on the next frame. According to Nvidia's hardware
engineers, there isn't any cleaner way of flipping notifier contexts
that would avoid this.
Since using vblank workers to swap out the notifier context will ensure
we can usually flush both updates to hardware within the timespan of a
single frame, we can also ensure that there will only be exactly one
frame lost between the first and second update being executed by the
hardware. This gives us the guarantee that we're always correctly
matching each CRC entry with it's respective frame even after a context
flip. And since IGT will retrieve the CRC entry for a frame by waiting
until it receives a CRC for any subsequent frames, this doesn't cause an
issue with any tests and is much simpler than trying to change the
current DRM API to accommodate.
In order to facilitate testing of correct handling of this limitation,
we also expose a debugfs interface to manually control the threshold for
when we start trying to flip the notifier context. We will use this in
igt to trigger a context flip for testing purposes without needing to
wait for the notifier to completely fill up. This threshold is reset
to the default value set by nouveau after each capture, and is exposed
in a separate folder within each CRTC's debugfs directory labelled
"nv_crc".
Changes since v1:
* Forgot to finish saving crc.h before saving, whoops. This just adds
some corrections to the empty function declarations that we use if
CONFIG_DEBUG_FS isn't enabled.
Changes since v2:
* Don't check return code from debugfs_create_dir() or
debugfs_create_file() - Greg K-H
Changes since v3:
(no functional changes)
* Fix SPDX license identifiers (checkpatch)
* s/uint32_t/u32/ (checkpatch)
* Fix indenting in switch cases (checkpatch)
Changes since v4:
* Remove unneeded param changes with nv50_head_flush_clr/set
* Rebase
Changes since v5:
* Remove set but unused variable (outp) in nv50_crc_atomic_check() -
Kbuild bot
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200627194657.156514-10-lyude@redhat.com
While we're not quite ready yet to add support for flexible wndw
mappings, we are going to need to at least keep track of the static wndw
mappings we're currently using in each head's atomic state. We'll likely
use this in the future to implement real flexible window mapping, but
the primary reason we'll need this is for CRC support.
See: on nvidia hardware, each CRC entry in the CRC notifier dma context
has a "tag". This tag corresponds to the nth update on a specific
EVO/NvDisplay channel, which itself is referred to as the "controlling
channel". For gf119+ this can be the core channel, ovly channel, or base
channel. Since we don't expose CRC entry tags to userspace, we simply
ignore this feature and always use the core channel as the controlling
channel. Simple.
Things get a little bit more complicated on gv100+ though. GV100+ only
lets us set the controlling channel to a specific wndw channel, and that
wndw must be owned by the head that we're grabbing CRCs when we enable
CRC generation. Thus, we always need to make sure that each atomic head
state has at least one wndw that is mapped to the head, which will be
used as the controlling channel.
Note that since we don't have flexible wndw mappings yet, we don't
expect to run into any scenarios yet where we'd have a head with no
mapped wndws. When we do add support for flexible wndw mappings however,
we'll need to make sure that we handle reprogramming CRC capture if our
controlling wndw is moved to another head (and potentially reject the
new head state entirely if we can't find another available wndw to
replace it).
With that being said, nouveau currently tracks wndw visibility on heads.
It does not keep track of the actual ownership mappings, which are
(currently) statically programmed. To fix this, we introduce another
bitmask into nv50_head_atom.wndw to keep track of ownership separately
from visibility. We then introduce a nv50_head callback to handle
populating the wndw ownership map, and call it during the atomic check
phase when core->assign_windows is set to true.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200627194657.156514-7-lyude@redhat.com
In order to be able to use bpc values that are different from what the
connector reports, we want to be able to store the bpc value we decide
on using for an atomic state in nv50_head_atom and refer to that instead
of simply using the value that the connector reports throughout the
whole atomic check phase and commit phase. This will let us (eventually)
implement the max bpc connector property, and will also be needed for
limiting the bpc we use on MST displays to 8 in the next commit.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: 232c9eec41 ("drm/nouveau: Use atomic VCPI helpers for MST")
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Juston Li <juston.li@intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: <stable@vger.kernel.org> # v5.1+
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Has a nice side-effect that we only update HW for this when it changes now,
rather than every time we do a page flip.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Atomic checks should never modify anything outside of the state that
they're passed in. Unfortunately this appears to be exactly what we're
doing in nv50_msto_atomic_check() where we update mstc->pbn every time
the function is called. This hasn't caused any bugs yet, but it needs to
be fixed in order to ensure that when committing an artificially
duplicated state (like during system resume), that we reuse the PBN of
that state to perform VCPI allocations and don't recalculate a different
value from the drm connector's reported bpc.
Also, move the VCPI slot allocations while we're at it as well. With
this, removing a topology in suspend while using nouveau no longer
causes the new atomic VCPI helpers to complain.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: eceae14724 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-5-lyude@redhat.com
Window visibility is going to become a little more complicated with the
upcoming LUT changes, so store the calculated value to avoid needing to
recalculate the armed state again.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
