Bspec asks us to always set the DSB_SKIP_WAITS_EN bit in
DSB_CHICKEN. This seems to instruct DSB to skip vblank and
scanline waits when PSR is entered.
I don't think we have any cases currently where we would want
to enter PSR while DSB is waiting for something, but let's
set the bit anyway to align with Bspec's wishes.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306040806.21697-4-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Looks like the undelayed vblank gets signalled exactly when
the active period ends. That is a problem for DSB+VRR when
we are already in vblank and expect DSB to start executing
as soon as we send the push. Instead of starting, the DSB
just keeps on waiting for the undelayed vblank which won't
signal until the end of the next frame's active period,
which is far too late.
The end result is that DSB won't have even started
executing by the time the flips/etc. have completed.
We then wait for an extra 1ms, after which we terminate
the DSB and report a timeout:
[drm] *ERROR* [CRTC:80:pipe A] DSB 0 timed out waiting for idle (current head=0xfedf4000, head=0x0, tail=0x1080)
To fix this let's configure DSB to use the so called VRR
"safe window" instead of the undelayed vblank to trigger
the DSB vblank logic, when VRR is enabled.
Cc: stable@vger.kernel.org
Fixes: 34d8311f4a ("drm/i915/dsb: Re-instate DSB for LUT updates")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9927
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306040806.21697-3-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
If fixed refresh rate program the PKGC_LATENCY register
with the highest latency from level 1 and above LP registers
and program ADDED_WAKE_TIME = DSB execution time.
else program PKGC_LATENCY with all 1's and ADDED_WAKE_TIME as 0.
This is used to improve package C residency by sending the highest
latency tolerance requirement (LTR) when the planes are done with the
frame until the next frame programming window (set context latency,
window 2) starts.
Bspec: 68986
--v2
-Fix indentation [Chaitanya]
--v3
-Take into account if fixed refrersh rate or not [Vinod]
-Added wake time dependengt on DSB execution time [Vinod]
-Use REG_FIELD_PREP [Jani]
-Call program_pkgc_latency from appropriate place [Jani]
-no need for the ~0 while setting max latency [Jani]
-change commit message to add the new changes made in.
--v4
-Remove extra blank line [Vinod]
-move the vrr.enable check to previous loop [Vinod]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219063638.1467114-1-suraj.kandpal@intel.com
Current, the dewake_scanline variable is defined as unsigned int,
an unsigned int variable that is always greater than or equal to 0.
when _intel_dsb_commit function is called by intel_dsb_commit function,
the dewake_scanline variable may have an int value.
So the dewake_scanline variable is necessary to defined as an int.
Fixes: f83b94d237 ("drm/i915/dsb: Use DEwake to combat PkgC latency")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310052201.AnVbpgPr-lkp@intel.com/
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: heminhong <heminhong@kylinos.cn>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231114024341.14524-1-heminhong@kylinos.cn
Refactor DSB implementation to be compatible with Xe driver.
v1: RFC version.
v2: Make intel_dsb structure opaque from external usage. [Jani]
v3: Rebased on latest.
v4:
- Add boundary check in dsb_buffer_memset(). [Luca]
- Use size_t instead of u32. [Luca]
v5: WARN_ON() added for out of boudary case with some optimization. [Luca]
v6: Rebased on latest and fix a rebase-miss.
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231110032518.3564279-1-animesh.manna@intel.com
The display engine does not snoop the caches so we should mark
the DSB command buffer as I915_CACHE_NONE.
i915_gem_object_create_internal() always gives us I915_CACHE_LLC
on LLC platforms. And to make things 100% correct we should also
clflush at the end, if necessary.
Note that currently this is a non-issue as we always write the
command buffer through a WC mapping, so a cache flush is not actually
needed. But we might actually want to consider a WB mapping since
we also end up reading from the command buffer (in the indexed
reg write handling). Either that or we should do something else
to avoid those reads (might actually be even more sensible on DGFX
since we end up reading over PCIe). But we should measure the overhead
first...
Anyways, no real harm in adding the belts and suspenders here so
that the code will work correctly regardless of how we map the
buffer. If we do get a WC mapping (as we request)
i915_gem_object_flush_map() will be a nop. Well, apart form
a wmb() which may just flush the WC buffer a bit earlier
than would otherwise happen (at the latest the mmio accesses
would trigger the WC flush).
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231009132204.15098-2-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Using system memory for the DSB command buffer doesn't appear to work.
On DG2 it seems like the hardware internally replaces the actual memory
reads with zeroes, and so we end up executing a bunch of NOOPs instead
of whatever commands we put in the buffer. To determine that I measured
the time it takes to execute the instructions, and the results are
always more or less consistent with executing a buffer full of NOOPs
from local memory.
Another theory I considered was some kind of cache coherency issue.
Looks like i915_gem_object_pin_map_unlocked() will in fact give you a
WB mapping for system memory on DGFX regardless of what mapping mode
was requested (WC in case of the DSB code). But clflush did not
change the behaviour at all, so that theory seems moot.
On DG1 it looks like the hardware might actually be fetching data from
system memory as the logs indicate that we just get underruns. But that
is equally bad, so doesn't look like we can really use system memory on
DG1 either.
Thus always allocate the DSB command buffer from local memory on
discrete GPUs.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231009132204.15098-1-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Normally we could be in a deep PkgC state all the way up to the
point when DSB starts its execution at the transcoders undelayed
vblank. The DSB will then have to wait for the hardware to
wake up before it can execute anything. This will waste a huge
chunk of the vblank time just waiting, and risks the DSB execution
spilling into the vertical active period. That will be very bad,
especially when programming the LUTs as the anti-collision logic
will cause DSB to corrupt LUT writes during vertical active.
To avoid these problems we can instruct the DSB to pre-wake the
display engine on a specific scanline so that everything will
be 100% ready to go when we hit the transcoder's undelayed vblank.
One annoyance is that the scanline is specified as just that,
a single scanline. So if we happen to start the DSB execution
after passing said scanline no DEwake will happen and we may drop
back into some PkgC state before reaching the transcoder's undelayed
vblank. To prevent that we'll use the "force DEwake" bit to manually
force the display engine to stay awake. We'll then have to clear
the force bit again after the DSB is done (the force bit remains
effective even when the DSB is otherwise disabled).
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-18-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Avoid the locking overhead for DSB registers. We don't need the locks
and intel_dsb_commit() in particular needs to be called from the
vblank evade critical section and thus needs to be fast.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-3-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
i915_gem_object_create_internal() does not hand out zeroed
memory. Thus we may confuse whatever stale garbage is in
there as a previous register write and mistakenly handle the
first actual register write as an indexed write. This can
end up corrupting the instruction sufficiently well to lose
the entire register write.
Make sure we've actually emitted a previous instruction before
attemting indexed register write merging.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-7-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Introduce a function to emits whatever commands we need
at the end of the DSB command buffer. For the moment we
only do the tail cacheline alignment there, but eventually
we might want to eg. emit an interrupt.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230118163040.29808-5-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Starting the DSB execution vs. waiting for it stop are two
totally different things. Split intel_dsb_wait() from
intel_dsb_commit() so that we can eventually allow the DSB
to execute asynchronously.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230118163040.29808-4-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
The caller should more or less know how many DSB commands it
wants to emit into the command buffer, so allow it to specify
the size of the command buffer rather than having the low level
DSB code guess it.
Technically we can emit as many as 134+1033 (for adl+ degamma +
10bit gamma) register writes but thanks to the DSB indexed register
write command we get significant space savings so the current size
estimate of 8KiB (~1024 DSB commands) is sufficient for now.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216003810.13338-11-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
The DSB indexed register write insturction is purely an internal
DSB implementation detail, no reason why the caller should have to
know about it. So let's just have the caller emit blind register
writes let the DSB code convert things to an indexed write if/when
multiple writes occur to the same register offset in a row.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216003810.13338-9-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Currently intel_dsb_indexed_reg_write() just assumes the previous
instructions is also an indexed register write, and thus only
checks the register offset. Make the check more robust by
actually checking the instruction opcode as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216003810.13338-8-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
free_pos is in dwords, DSB_BUF_SIZE in bytes. Directly
comparing the two is nonsense. Fix it up, and make sure
we also account for the 8byte alignment requirement for
each instruction, and also assume that each instruction
normally eats two dwords.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216003810.13338-5-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Every DSB instruction has to be 8byte aligned. Make sure
that is the case for the non-indexed register writes as well.
The way this could end up unaligned is we emitted an odd
number of indexed register writes beforehand.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216003810.13338-4-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
We could have many different uses for the DSB(s) during a
single commit, so the current approach of passing the whole
crtc_state to the DSB functions is far too high level. Lower
the abstraction a little bit so each DSB user can decide where
to stick the command buffer/etc.
v2: Document the intel_dsb_prepare() return value (Ankit)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221123152638.20622-10-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
The use of DSB has to be done differently on a case by case basis.
So no way this kind of blind mmio fallback in the guts of the DSB
code will work properly. Move it at least one level up into the
LUT loading code. Not sure if this is the way we want do the
DSB vs. mmio handling in the end, but at least it's a bit
closer than what we had before.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221123152638.20622-8-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Turns out many of the files that need i915_reg.h get it implicitly via
{display/intel_de.h, gt/intel_context.h} -> i915_trace.h -> i915_irq.h
-> i915_reg.h. Since i915_trace.h doesn't actually need i915_irq.h,
makes sense to drop it, but that requires adding quite a few new
includes all over the place.
Prefer including i915_reg.h where needed instead of adding another
implicit include, because eventually we'll want to split up i915_reg.h
and only include the specific registers at each place.
Also some places actually needed i915_irq.h too.
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6e78a2e0ac1bffaf5af3b5ccc21dff05e6518cef.1668008071.git.jani.nikula@intel.com
The request to aqquire gem resources is failing for DSB in rare
scenario where it is busy and the register programming will be done
through mmio fallback path.
DSB has extra advantage of faster register programming which may
go away through mmio path. Adding wait for gem resource also may
not be right as anyways losing time.
To make the CI execution happy replaced drm_err() to drm_info()
for printing debug info during dsb buffer preparation.
v1: Initial version.
v2: Added print for mmio fallback at out label. [Nirmoy]
v3: Improved debug message. [Nirmoy]
Cc: Nirmoy Das <nirmoy.das@linux.intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220325161140.11906-1-animesh.manna@intel.com
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
We have to bash in a lot of registers to load the higher
precision LUT modes. The locking overhead is significant, especially
as we have to get this done as quickly as possible during vblank.
So let's switch to unlocked accesses for these. Fortunately the LUT
registers are mostly spread around such that two pipes do not have
any registers on the same cacheline. So as long as commits on the
same pipe are serialized (which they are) we should get away with
this without angering the hardware.
The only exceptions are the PREC_PIPEGCMAX registers on ilk/snb which
we don't use atm as they are only used in the 12bit gamma mode. If/when
we add support for that we may need to remember to still serialize
those registers, though I'm not sure ilk/snb are actually affected
by the same cacheline issue. I think ivb/hsw at least were, but they
use a different set of registers for the precision LUT.
I have a test case which is updating the LUTs on two pipes from a
single atomic commit. Running that in a loop for a minute I get the
following worst case with the locks in place:
intel_crtc_vblank_work_start: pipe B, frame=10037, scanline=1081
intel_crtc_vblank_work_start: pipe A, frame=12274, scanline=769
intel_crtc_vblank_work_end: pipe A, frame=12274, scanline=58
intel_crtc_vblank_work_end: pipe B, frame=10037, scanline=74
And here's the worst case with the locks removed:
intel_crtc_vblank_work_start: pipe B, frame=5869, scanline=1081
intel_crtc_vblank_work_start: pipe A, frame=7616, scanline=769
intel_crtc_vblank_work_end: pipe B, frame=5869, scanline=1096
intel_crtc_vblank_work_end: pipe A, frame=7616, scanline=777
The test was done on a snb using the 10bit 1024 entry LUT mode.
The vtotals for the two displays are 793 and 1125. So we can
see that with the locks ripped out the LUT updates are pretty
nicely confined within the vblank, whereas with the locks in
place we're routinely blasting past the vblank end which causes
visual artifacts near the top of the screen.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020223339.669-5-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Hoist the intel_de.h include from intel_display_types.h one
level up. I need this in order to untangle the include order
so that I can add tracepoints into intel_de.h.
This little cocci script did most of the work for me:
@find@
@@
(
intel_de_read(...)
|
intel_de_read_fw(...)
|
intel_de_write(...)
|
intel_de_write_fw(...)
)
@has_include@
@@
(
#include "intel_de.h"
|
#include "display/intel_de.h"
)
@depends on find && !has_include@
@@
+ #include "intel_de.h"
#include "intel_display_types.h"
@depends on find && !has_include@
@@
+ #include "display/intel_de.h"
#include "display/intel_display_types.h"
Cc: Cooper Chiou <cooper.chiou@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210430143945.6776-1-ville.syrjala@linux.intel.com
Because of the long lifetime of the mapping, we cannot wrap this in a
simple limited ww lock. Just use the unlocked version of pin_map,
because we'll likely release the mapping a lot later, in a different
thread.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-39-maarten.lankhorst@linux.intel.com
Currently there is no null check for a failed memory allocation
on the dsb object and without this a null pointer dereference
error can occur. Fix this by adding a null check.
Note: added a drm_err message in keeping with the error message style
in the function.
Addresses-Coverity: ("Dereference null return")
Fixes: afeda4f3b1 ("drm/i915/dsb: Pre allocate and late cleanup of cmd buffer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200616114221.73971-1-colin.king@canonical.com
drivers/gpu/drm/i915/display/intel_dsb.c:177 intel_dsb_reg_write() warn: variable dereferenced before check 'dsb' (see line 175)
Fixes: afeda4f3b1 ("drm/i915/dsb: Pre allocate and late cleanup of cmd buffer")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Animesh Manna <animesh.manna@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200524233900.25598-1-chris@chris-wilson.co.uk
Pre-allocate command buffer in atomic_commit using intel_dsb_prepare
function which also includes pinning and map in cpu domain.
No functional change is dsb write/commit functions.
Now dsb get/put function is removed and ref-count mechanism is
not needed. Below dsb api added to do respective job mentioned
below.
intel_dsb_prepare - Allocate, pin and map the buffer.
intel_dsb_cleanup - Unpin and release the gem object.
RFC: Initial patch for design review.
v2: included _init() part in _prepare(). [Daniel, Ville]
v3: dsb_cleanup called after cleanup_planes. [Daniel]
v4: dsb structure is moved to intel_crtc_state from intel_crtc. [Maarten]
v5: dsb get/put/ref-count mechanism removed. [Maarten]
v6: Based on review feedback following changes are added,
- replaced intel_dsb structure by pointer in intel_crtc_state. [Maarten]
- passing intel_crtc_state to dsp-api to simplify the code. [Maarten]
- few dsb functions prototype modified to simplify code.
v7: added few cosmetic changes suggested by Jani and null check for
crtc_state in dsb_cleanup removed as suggested by Maarten.
v8: changed the function parameter to intel_crtc_state* of
ivb_load_lut_ext_max() from intel_crtc. [Maarten]
v9: error handling improved in _write() and prepare(). [Maarten]
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200520130737.11240-1-animesh.manna@intel.com
Remove a number of inlines from .c files, and let the compiler decide
what's best. There's more to do, but need to start somewhere, and need
to start setting the example.
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200420140438.14672-2-jani.nikula@intel.com
