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Current DSB hardware is apparently a bit borked and likes to signal
spurious GOSUB errors. We already have most for the workarounds for
this in place, but the last part is simply not enabling the corresponding
interrupt.
While at it polish up the w/a comments with the w/a number,
and consistently take the short blurp from the w/a page.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-7-ville.syrjala@linux.intel.com
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When using the flip queue, due to the DMC vs. DSB register corruption
problem, we must not issue any register writes from the DSB after
unhalting the DMC. Currently we are doing just that by trying to
restore DSB_PMCTRL* back to a sane state from intel_dsb_finish().
Since the only place left that pokes at DSB_PMCTRL* is intel_dsb_chain()
we can just do DSB_PMCTRL_2/DSB_FORCE_DEWAKE reset in the same place.
The DSB_PMCTRL reset is trickier since we'd have to do it from the
chained DSB itself. But based on my earlier testing
DSB_PMCTRL/DSB_ENABLE_DEWAKE doesn't actually do anything if the DSB
isn't actually enabled, so we can omit the reset to keep things a bit
simpler. We do need to reset DSB_PMCTRL/DSB_ENABLE_DEWAKE before
tarting the DSB however, in case it was left enabled from a previous
use.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-6-ville.syrjala@linux.intel.com
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Since the introduction of DSB chaining we no longer need the
DEwake tricks in intel_dsb_commit().
I also need to relocate the DSB_PMCTRL* writes out of
intel_dsb_finish() (due to the flip queue DMC vs. DSB register
corruption issues), and it'll be a bit more straightforward if
I don't have to worry about the non-chained DSB path anymore.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-5-ville.syrjala@linux.intel.com
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Pull the magic 20 usec DSB execution deadline into
intel_dsb_arm_exec_time_us(), and also add its counterpart
for the non-arming register write section. For the non-arming
part we'll just throw in a random 80 usec for now so the total
is 100usec. The total exec time will be needed by the upcoming
flip queue code.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-4-ville.syrjala@linux.intel.com
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The upcoming flip queue implementation will need to know the
DSB buffer head and size. Expose those outside intel_dsb.c.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-3-ville.syrjala@linux.intel.com
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If the free_post is not QW aligned we don't have to memset the
extra DW needed to make it so, as the only way that can happen
is via intel_dsb_reg_write_indexed() which already makes sure
the next DW is zeroed.
Not a big deal, but this is more consistent how all the other
stuff operates that puts instructions into the DSB buffer, and
we'll get a few more of those soon.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250612145018.8735-2-ville.syrjala@linux.intel.com
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A number of files have unnecessary i915_reg.h includes. Drop them.
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Link: https://lore.kernel.org/r/7c4002322f4d8132fd2eaa1a4d688539cdd043c3.1749469962.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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This is a scripted split of the display related register macros from
i915_reg.h to display/intel_display_regs.h. As a starting point, move
all the macros that are only used in display code (or GVT). If there are
users in core i915 code or soc/, or no users anywhere, keep the macros
in i915_reg.h. This is done in groups of macros separated by blank
lines, moving the comments along with the groups.
Some manually picked macro groups are kept/moved regardless of the
heuristics above.
This is obviously a very crude approach. It's not perfect. But there are
4.2k lines in i915_reg.h, and its refactoring has ground to a halt. This
is the big hammer that splits the file to two, and enables further
cleanup.
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com> # v2
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250606102256.2080073-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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DSB raises an interrupt when there is a nested GOSUB command or
illegal Head/Tail. Add support to log such errors in the DSB
interrupt handler.
v2: Enable support only in platforms that support this (Ville)
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-7-chaitanya.kumar.borah@intel.com
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A DSB buffer which will be used for GOSUB execution does not need
the DEWAKE mechanism but still need to be 64 bit aligned. Add helper
to finish preparation of a dsb buffer to be executed with GOSUB
instruction.
v2: Add a cacheline of noops at the end of GOSUB buffer (Ville)
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-6-chaitanya.kumar.borah@intel.com
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Add support for the new GOSUB DSB instruction (available on ptl+),
which instructs the DSB to jump to a different buffer, execute
the commands there, and then return execution to the next
instruction in the original buffer.
There are a few alignment related workarounds that need to
be dealt with when emitting GOSUB instruction.
v2: Right shift head and tail pointer passed to gosub command (chaitanya)
v3: Add macro for right shifting head/tail pointers (Animesh)
v4: Fix typo in commit message (Uma)
Add comments explaining why right shifting htp is needed (Animesh)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-5-chaitanya.kumar.borah@intel.com
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Extract the code that calculates the DSB_HEAD/TAIL register
values into small helpers. We already have two copies of this,
and soon there will be a third.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-4-chaitanya.kumar.borah@intel.com
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Extract the DSB tail alignment checks into helper. We already
have two uses of this, and soon we'll get a third.
v2: s/soo/soon in commit message (Animesh)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-3-chaitanya.kumar.borah@intel.com
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Extract the code that alings the next instruction to the next
QW boundary into a small helper. I'll have some more uses for
this later.
Also explain why we don't have to zero out the extra DW.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250523062041.166468-2-chaitanya.kumar.borah@intel.com
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These includes have become unnecessary. Drop them.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/6ca3be3e3fbbd99c169345c3add4b76315390e77.1747128495.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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With the PCH macros switched to use struct intel_display, we have a
number of files that no longer need struct drm_i915_private or anything
else from i915_drv.h anymore. Remove the #include, and add the missing
includes that were previously implicit.
v2: Drop even more of the includes
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://lore.kernel.org/r/5dc9e6a98461c344febac4c645875d8688eba906.1744880985.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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Going forward, struct intel_display is the main display device data
pointer. Convert the skl_watermark.h interface to struct intel_display.
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/cd2b1863dee25b69b4766090dd183a7467c4edea.1744119460.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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Convert i915 runtime PM interfaces to display runtime PM interfaces all
over the place in display code.
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/494d0bd0348e4aa99560f1aed21aaaff31706c44.1742483007.git.jani.nikula@intel.com
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PIPEDSL is reading as 0 when in SRDENT(PSR1) or DEEP_SLEEP(PSR2). On
wake-up scanline counting starts from vblank_start - 1. We don't know if
wake-up is already ongoing when evasion starts. In worst case PIPEDSL could
start reading valid value right after checking the scanline. In this
scenario we wouldn't have enough time to write all registers. To tackle
this evade scanline 0 as well. As a drawback we have 1 frame delay in flip
when waking up.
v2:
- use intel_dsb_emit_wait_dsl
- add evasion of scanline 0 also for Panel Replay
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250213064804.2077127-11-jouni.hogander@intel.com
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We have different approach on how flip is considered being complete. We are
waiting for vblank on DSB and generate interrupt when it happens and this
interrupt is considered as indication of completion -> we definitely do not
want to skip vblank wait.
Also not skipping scanline wait shouldn't cause any problems if we are in
DEEP_SLEEP PIPEDSL register is returning 0 -> evasion does nothing and if
we are not in DEEP_SLEEP evasion works same way as without PSR.
v2: add comment explaining why we are not setting DSB_SKIP_WAITS_EN
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250213064804.2077127-10-jouni.hogander@intel.com
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Decode the DSB error interrupts into human readable
form for easier debugging.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250207223159.14132-9-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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Add a function for emitting a DSB poll instruction. We'll allow
the caller to specify the poll parameters.
v2: s/wait/wait_us/ (Ankit)
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250207223159.14132-6-ville.syrjala@linux.intel.com
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When we send a push during vblank the TRANS_PUSH write happens
at some point during a scanline, and the hardware picks it up
on the next scanline. Thus there is up to one extra scanline
of delay between the TRANS_PUSH write and the delayed vblank
triggering. Account for that during intel_dsb_wait_vblank_delay()
so that we are guaranteed to be past the delayed vblank before
we trigger the completion interrupt for the commit.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250207223159.14132-4-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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The "wait usec" DSB command doesn't quite seem to able to
guarantee that it always waits at least the specified
amount of usecs. Some of that could be just because it
supposedly just does some kind of dumb timestamp comparison
internally. But I also see cases where two hardware timestamps
sampled on each side of the "wait usec" command come out one
less than expected. So it looks like we always need at least a
+1 to guarantee that we never wait less than specified. Always
apply that adjustment in dsb_wait_usec().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250207223159.14132-2-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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Fix all typos in files under drm/i915/display reported by codespell tool.
v2:
- Include british and american spelling, as those are
not typos.
- Fix commenting style. <Jani>
v3: Fix "In case" wrongly capitalized and
also fix comment style. <Krzysztof Niemiec>
Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
Reviewed-by: Krzysztof Niemiec <krzysztof.niemiec@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250120081517.3237326-8-nitin.r.gote@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Introduce a VRR specific function for determining the current
vblank delay. Currently thus will give the same answer as
intel_mode_vblank_delay() but that will change later.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210211007.5976-13-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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We have approximately two copies of pre_commit_crtc_state(),
one in the DSB code, the other in the vblank evasion code.
Combine them into one. The slight difference between the two
is that vblank evasion doesn't have a full atomic state (when
called from the legacy cursor code), so it gets the old and
new crtc state passed in by hand.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210211007.5976-11-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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Extract the code that computes the hardware centric view
of the vblank delay into a helper. We'll need a slightly
different variant for VRR soon.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210211007.5976-10-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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On ICL/TGL vmin/vmax/flipline won't actually match the
vtotal values (currently they do, but that is wrong and
needs to be fixed). Add a few helpers that will compute the
actual vtotal values for us.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210211007.5976-5-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
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We've determined that indexed DSB writes are only faster
than MMIO writes when writing the same register ~5 or more
times. That seems very unlikely to happen in any other case
than when using indexed LUT registers. Simplify the code
by removing the MMIO->indexed write conversion logic and
just emit the instruction as an indexed write from the get go.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241120164123.12706-4-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
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Turns out the DSB indexed register write command has
rather significant initial overhead compared to the normal
MMIO write command. Based on some quick experiments on TGL
you have to write the register at least ~5 times for the
indexed write command to come out ahead. If you write the
register less times than that the MMIO write is faster.
So it seems my automagic indexed write logic was a bit
misguided. Go back to the original approach only use
indexed writes for the cases we know will benefit from
it (indexed LUT register updates).
Currently we shouldn't have any cases where this truly
matters (just some rare double writes to the precision
LUT index registers), but we will need to switch the
legacy LUT updates to write each LUT register twice (to
avoid some palette anti-collision logic troubles).
This would be close to the worst case for using indexed
writes (two writes per register, and 256 separate registers).
Using the MMIO write command should shave off around 30%
of the execution time compared to using the indexed write
command.
Cc: stable@vger.kernel.org
Fixes: 34d8311f4a1c ("drm/i915/dsb: Re-instate DSB for LUT updates")
Fixes: 25ea3411bd23 ("drm/i915/dsb: Use non-posted register writes for legacy LUT")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241120164123.12706-2-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
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Needed to bring some KVM changes to be able to include a fix in our Kconfig.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Add intel_dsb_wait_vblank_delay() which instructs the DSB
to wait for duration between the undelayed and delayed vblanks.
We'll need this as the DSB can only directly wait for the
undelayed vblank, but we'll need to wait until the delayed
vblank has elapsed as well.
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-10-ville.syrjala@linux.intel.com
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Add a function to emit a DSB wait for vblank instruction. This
just waits until the specified number of vblanks.
Note that this triggers on the transcoder's undelayed vblank,
as opposed to the pipe's delayed vblank.
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-8-ville.syrjala@linux.intel.com
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Add a function to emit the DSB "wait usecs" instruction.
This is just a usleep() for the DSB.
As a lower bound it seems pretty accurate, but the upper bound
seemed oddly relaxed (ie. sometimes I've seen waits that are
quite a bit longer than specified, not sure why).
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-7-ville.syrjala@linux.intel.com
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Add a helper for performing vblank evasion on the DSB. DSB based
plane updates will need this to guarantee all the double buffered
arming registers will get programmed atomically within the same
frame.
With VRR we more or less have two vblanks to worry about:
- vmax vblank start in case no push was sent
- vmin vblank start in case a push was already sent during
the vertical active. Only a concern for mailbox updates,
which I suppose could happen if the legacy cursor updates
take the non-fastpath without setting
state->legacy_cursor_update to false.
Since we don't know which case is relevant we'll just evade
both.
We must also make sure to evade both the delayed vblank
(for pipe/plane registers) and the undelayed vblank
(for transcoder registers and chained DSBs w/
DSB_WAIT_FOR_VBLANK).
TODO: come up with a sensible usec number for the evasion...
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-6-ville.syrjala@linux.intel.com
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The DSB can signal a programmable interrupt in response to
a specific DSB command getting executed. Hook that up.
For now we'll just use this to signal the completion of the
commit via a vblank event. If, in the future, we'll need to
do other things in response to DSB interrupts we may need to
come up with some kind of fancier DSB interrupt framework where
the caller can specify a custom handler...
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-5-ville.syrjala@linux.intel.com
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Reading from the DSB command buffer might be somewhat expensive on
discrete GPUs because the buffer resides in GPU local memory. Avoid
such reads in the indexed register write handling by tracking the
previous instruction in intel_dsb.
TODO: actually measure this
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-2-ville.syrjala@linux.intel.com
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This reverts commit c27f010aa1884276ee5dae72034d84987060c769.
After fix from [1] dsb timeout issue is not reproducible on local testing
with xe driver. Checking CI result to confirm and not for review.
[1] https://patchwork.freedesktop.org/series/130783/
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240913114754.7956-3-maarten.lankhorst@linux.intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
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Convert the intel_crtc_for_pipe() struct drm_i915_private parameter to
struct intel_display.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240904130633.3831492-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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In order to avoid the DSB keeping the DEwake permanently
asserted we must clear DSB_PMCTRL_2.DSB_FORCE_DEWAKE once
we are done. For good measure do the same for
DSB_PMCTRL.DSB_ENABLE_DEWAKE.
Experimentally this doens't seem to be actually necessary
(unlike with DSB_FORCE_DEWAKE). That is, the DSB_ENABLE_DEWAKE
doesn't seem to do anything whenever the DSB is not active.
But I'd hate to waste a ton of power in case there I'm wrong
and there is some way DEwake could remaing asserted. One extra
register write is a small price to pay for some peace of mind.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-13-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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Allow intel_dsb_chain() to start the chained DSB
at start of the undelaye vblank. This is slightly
more involved than simply setting the bit as we
must use the DEwake mechanism to eliminate pkgC
latency.
And DSB_ENABLE_DEWAKE itself is problematic in that
it allows us to configure just a single scanline,
and if the current scanline is already past that
DSB_ENABLE_DEWAKE won't do anything, rendering the
whole thing moot.
The current workaround involves checking the pipe's current
scanline with the CPU, and if it looks like we're about to
miss the configured DEwake scanline we set DSB_FORCE_DEWAKE
to immediately assert DEwake. This is somewhat racy since the
hardware is making progress all the while we're checking it on
the CPU.
We can make things less racy by chaining two DSBs and handling
the DSB_FORCE_DEWAKE stuff entirely without CPU involvement:
1. CPU starts the first DSB immediately
2. First DSB configures the second DSB, including its dewake_scanline
3. First DSB starts the second w/ DSB_WAIT_FOR_VBLANK
4. First DSB asserts DSB_FORCE_DEWAKE
5. First DSB waits until we're outside the dewake_scanline-vblank_start
window
6. First DSB deasserts DSB_FORCE_DEWAKE
That will guarantee that the we are fully awake when the second
DSB starts to actually execute.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-12-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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In order to handle the DEwake tricks without involving
the CPU we need a mechanism by which one DSB can start
another one. Add a basic function to do so. We'll extend
it later with additional code to actually deal with
DEwake.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-11-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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Add functions to emit a DSB scanline window wait instructions.
We can either wait for the scanline to be IN the window
or OUT of the window.
The hardware doesn't handle wraparound so we must manually
deal with it by swapping the IN range to the inverse OUT
range, or vice versa.
Also add a bit of paranoia to catch the edge case of waiting
for the entire frame. That doesn't make sense since an IN
wait would be a nop, and an OUT wait would imply waiting
forever. Most of the time this also results in both scanline
ranges (original and inverted) to have lower=upper+1
which is nonsense from the hw POV.
For now we are only handling the case where the scanline wait
happens prior to latching the double buffered registers during
the commit (which might change the timings due to LRR/VRR/etc.)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-10-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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Adjust the code that determines the correct DSB_CHICKEN value
to be usable for use within DSB commands themselves. Ie.
precompute it based on our knowledge of what the hardware state
(VRR vs. not mainly) will be at the time of the commit.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-9-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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When determining various scanlines for DSB use we should take into
account whether VRR is active at the time when the DSB uses said
scanline information. For now all DSB scanline usage occurs prior
to the actual commit, so we only need to care about the state of
VRR at that time.
I've decided to move intel_crtc_scanline_to_hw() in its entirety
to the DSB code as it will also need to know the actual state
of VRR in order to do its job 100% correctly.
TODO: figure out how much of this could be moved to some
more generic place and perhaps be shared with the CPU
vblank evasion code/etc...
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-8-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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Currently we calculate the DEwake scanline based on
the delayed vblank start, while in reality it should be computed
based on the undelayed vblank start (as that is where the DSB
actually starts). Currently it doesn't really matter as we
don't have any vblank delay configured, but that may change
in the future so let's be accurate in what we do.
We can also remove the max() as intel_crtc_scanline_to_hw()
can deal with negative numbers, which there really shouldn't
be anyway.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-7-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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Relocate intel_dsb_dewake_scanline() and dsb_chicken() upwards
in the file. I need to reuse these while emitting DSB
commands, and I'd like to keep the DSB command emission
stuff more or less grouped together in the file.
Also drop the intel_ prefix from intel_dsb_dewake_scanline() since
it's all internal stuff and thus doesn't need so much namespacing.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-6-ville.syrjala@linux.intel.com
Reviewed-by: Animesh manna <animesh.manna@intel.com>
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Currently we switch from out software idea of a scanline
to the hw's idea of a scanline during the commit phase in
_intel_dsb_commit(). While that is slightly easier due to
fastsets fiddling with the timings, we'll also need to
generate proper hw scanline numbers already when emitting
DSB scanline wait instructions. So this approach won't
do in the future. Switch to hw scanline numbers earlier.
Also intel_dsb_dewake_scanline() itself already makes
some assumptions about VRR that don't take into account
VRR toggling during fastsets, so technically delaying
the sw->hw conversion doesn't even help us.
The other reason for delaying the conversion was that we
are using intel_get_crtc_scanline() during intel_dsb_commit()
which gives us the current sw scanline. But this is pretty
low level stuff anyway so just using raw PIPEDSL reads seems
fine here, and that of course gives us the hw scanline
directly, reducing the need to do so many conversions.
v2: Return the non-hw scanline from intel_dsb_dewake_scanline()
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/20240624191032.27333-5-ville.syrjala@linux.intel.com
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Enable all DSB error/fault interrupts so that we can see if
anything goes terribly wrong.
v2: Pass intel_display to DISPLAY_VER() (Jani)
Drop extra '/' from drm_err() for consistency
v3: Reorder the irq handler a bit
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240625135852.13431-1-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
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