When it comes to gamma or degamma luts, nouveau will actually skip the
calculation of certain LUTs depending on the head and plane states. For
instance, when the head is disabled we don't perform any error checking on
the gamma LUT, and likewise if no planes are present and enabled in our
atomic state we will skip error checking the degamma LUT. This is a bit of
a problem though, since the per-head gamma and degamma props in DRM can be
changed even while a head is disabled - a situation which can be triggered
by the igt testcase mentioned down below.
Originally I thought this was a bit silly and was tempted to just fix the
igt test to only set gamma/degamma with the head enabled. After a bit of
thinking though I realized we should fix this in nouveau. This is because
if a program decides to set an invalid LUT for a head before enabling the
head, such a property change would succeed while also making it impossible
to turn the head back on until the LUT is removed or corrected - something
that could be painful for a user to figure out.
So, fix this checking both degamma and gamma LUTs unconditionally during
atomic checks. We start by calling nv50_head_atomic_check_lut() regardless
of whether the head is active or not in nv50_head_atomic_check(). Then we
move the ilut error checking into nv50_head_atomic_check_lut() and add a
per-head hook for it, primarily because as a per-CRTC property DRM we want
the LUT to be error checked by the head any time it's included in an atomic
state. Of course though, actual programming of the degamma lut to hardware
is still handled in each plane's atomic check and commit.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Testcase: igt/kms_color/pipe-invalid-*-lut-sizes
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/10
This was a mistake that was present before, but never got noticed until
we converted over to using nvidia's class headers for display
programming. Luckily though it never caused any problems, since we
always end up calling crc907d_set_src() after head907d_mode().
So, let's get rid of this.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
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
The hardware supports either size. Also add checks to ensure that only
these two sizes may be used for supplying a LUT.
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Lyude Paul