On MST links - at least for some MST branch devices - the list of modes
returned to users on an enabled link depends on the current link
rate/lane count parameters (besides the DPRX link capabilities, any MST
branch BW limit and the maximum link parameters reduced after LT
failures). In particular the MST branch BW limit may depend on the link
rate/lane count parameters programmed to DPCD. After an LT failure and
limiting the maximum link parameters accordingly, users should see a
mode list reflecting these new limits. However with the current fallback
order this isn't ensured, as the new limit could allow for modes
requiring a higher link BW, but these modes will be filtered out due to
the enabled link's lower link BW.
Ensure that the mode list changes in a consistent way after a link
training failure and reducing the link parameters by changing the
fallback order on MST links to happen in BW order.
v2:
- s/INTEL_DP_MAX_SUPPORTED_LANE_COUNTS/INTEL_DP_MAX_SUPPORTED_LANE_CONFIGS
and s/num_common_lane_counts/num_common_lane_configs to make the
difference wrt. max lane counts clearer. (Suraj)
- Add a TODO comment to make the SST fallback logic work the same way as
MST. (Arun)
- Use sort_r()'s default swap function instead of a custom one.
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240729144458.2763667-1-imre.deak@intel.com
After the previous patch link training happens always with a valid
atomic state, so remove the NOTE comments and asserts which required a
valid state only for DP-MST and allowed for a NULL state for DP-SST.
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240712135724.660399-2-imre.deak@intel.com
Nothing depends on the cached LTTPR mode, however for consistency keep
it up-to-date with the value programmed to the DPCD register.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708190029.271247-5-imre.deak@intel.com
After detection the cached LTTPR count can be checked to determine if
LTTPRs in non-transparent mode were detected. Reset the cached LTTPR
count if the reported number of LTTPRs is invalid to ensure the above
checks work as expected.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708190029.271247-4-imre.deak@intel.com
Switching to transparent mode leads to a loss of link synchronization,
so prevent doing this on an active link. This happened at least on an
Intel N100 system / DELL UD22 dock, the LTTPR residing either on the
host or the dock. To fix the issue, keep the current mode on an active
link, adjusting the LTTPR count accordingly (resetting it to 0 in
transparent mode).
v2: Adjust code comment during link training about reiniting the LTTPRs.
(Ville)
Fixes: 7b2a4ab8b0 ("drm/i915: Switch to LTTPR transparent mode link training")
Reported-and-tested-by: Gareth Yu <gareth.yu@intel.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10902
Cc: <stable@vger.kernel.org> # v5.15+
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708190029.271247-3-imre.deak@intel.com
Add a connector debugfs entry to force retrain an active link. This can
be used to test both custom link parameters (previously forced via the
force_link_rate/lane_count entries) or link train failure scenarios
(previously forced via the force_link_training_failure entry). The entry
will autoreset after the link-retrain is complete.
v2: Add the entry from intel_dp_link_training.c (Jani)
v3: Lock connection_mutex only for the required intel_dp state. (Ville)
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-21-imre.deak@intel.com
Add a connector debugfs entry to force a failure during the following
1-2 link training. The entry will auto-reset after the specified link
training events are complete.
v2: Add the entry from intel_dp_link_training.c (Jani)
v3: Lock connection_mutex only for the required intel_dp state. (Ville)
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-20-imre.deak@intel.com
Add connector debugfs entries to get the maximum link rate and lane
count.
v2: Lock connection_mutex only for the required intel_dp state. (Ville)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-19-imre.deak@intel.com
Add connector debugfs entries to force the link rate/lane count to be
used by a link training afterwards. These settings will be clamped to
the supported, i.e. the source's and sink's common rate/lane count.
After forcing the link rate/lane count reset the link training
parameters and for a non-auto setting disable reducing the link
parameters via the fallback logic. The former one can be used after
testing link training failure scenarios - via debugfs entries added
later - to reset the reduced link parameters after the test.
v2:
- Add the entries from intel_dp_link_training.c (Jani)
- Rename the entries to i915_dp_set_link_rate/lane_count.
v3: (Ville)
- Rename the entries/struct fields to force_link_rate/lane_count.
- Lock connection_mutex only for the required intel_dp state.
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-18-imre.deak@intel.com
Reduce the link parameters after a link training failure for MST
outputs, similarly to how this is done for SST.
For now allow the reduction only by staying in the 8b/10b vs. 128b/132b
mode. Enabling the mode switch is left for a follow-up patchset, after
taking measures ensuring that the mode switch happens properly. In
particular a rediscovery of the whole MST topology may be required for
such a switch, see the References below.
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10970
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-17-imre.deak@intel.com
After a link training failure if the link parameters can't be further
reduced, there is no point in trying to retrain the link in the driver.
This avoids excessive retrain attempts after detecting a bad link, for
instance while handling MST HPD IRQs, which is likely redundant as the
link training failed already twice with the same minimum link
parameters. Userspace can still try to retrain the link with these
parameters via a modeset.
While at it make the error message more accurate.
v2: Move converting the error to a debug message to the relevant
follow-up patch. (Ville)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-15-imre.deak@intel.com
Send a modeset-retry uevent to all connectors in the same MST topology
after a link training failure and reduction of the link parameters. This
matches the way the same uevent is sent after a DP tunnel BW allocation
failure.
v2: Add NOTE that the atomic state may not be valid for SST links and
assert that it's valid for MST links. (Ville)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-11-imre.deak@intel.com
The next patch adds sending a modeset-retry uevent after a link training
failure to all MST connectors on link. This requires the atomic state,
so pass it to intel_dp_start_link_train(). In case of SST where
retraining still happens by calling this function directly instead of a
modeset commit the atomic state is not available and NULL is passed
instead. This is ok, since in this case the encoder's only DP connector
is available from intel_dp->attached_connector not requiring the atomic
state.
v2: Add NOTE that the atomic state may not be valid for SST links and
assert that it's valid for MST links. (Ville)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-10-imre.deak@intel.com
Try to maintain the current link parameters by retrying the link
training with unchanged link parameters before reducing these parameters
(sending an uevent to userspace to retrain the link instead).
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-9-imre.deak@intel.com
Recheck the link state after a passing link training, with a 2 sec delay
to account for cases where the link goes bad following the link training
and the sink doesn't report this via an HPD IRQ.
The delayed work added here will be also used by a later patch after a
failed link training to try to retrain the link with unchanged link
params before reducing the link params.
v2: Don't flush an uninitialized delayed work (on HDMI-only DDI ports).
v3:
- Move the helpers to a new intel_encoder.c file, rename them
accordingly. (Ville)
- Add the work to intel_encoder instead of intel_digital_port.
- Call the encoder specific link check function via an encoder hook.
- Flush the link check work during encoder destroy from
intel_dp_encoder_flush_work().
- Flush the link check work during encoder suspend as well.
v4: Call intel_encoder_link_check_init() with a valid encoder pointer.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610181428.2955658-1-imre.deak@intel.com
Reduce the indentation in intel_dp_get_link_train_fallback_values() by
adding separate helpers to reduce the link rate and lane count. Also
simplify things by passing crtc_state to the function.
This also prepares for later patches in the patchset adding a limitation
on how the link params are reduced.
While at it use lt_dbg()/lt_err() for debug/error prints in the function
which will also print the connector/encoder prefix and add a debug print
about reducing the link parameters.
v2:
- Align reduce_lane_count()'s error handling flow with
reduce_link_rate(). (Ville, Jani)
- Use lt_dbg()/lt_err() in the function.
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-5-imre.deak@intel.com
Move the functions used to reduce the link parameters during link
training to intel_dp_link_training.c .
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Manasi Navare <navaremanasi@chromium.org>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-4-imre.deak@intel.com
Factor out a function to read the sink's DPRX capabilities used by a
follow-up patch enabling the DP tunnel BW allocation mode.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240220211841.448846-10-imre.deak@intel.com
On shared (Thunderbolt) links with DP tunnels, the modeset may need to
be retried on all connectors on the link due to a link BW limitation
arising only after the atomic check phase. To support this add a helper
function queuing a work to retry the modeset on a given port's connector
and at the same time any MST connector with streams through the same
port. A follow-up change enabling the DP tunnel Bandwidth Allocation
Mode will take this into use.
v2:
- Send the uevent only to enabled MST connectors. (Jouni)
Cc: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240220211841.448846-5-imre.deak@intel.com
The eDP 1.5 spec adds a clarification for eDP 1.4x:
> For eDP v1.4x, if the Source device chooses the Main-Link rate by way
> of DPCD 00100h, the Sink device shall ignore DPCD 00115h[2:0].
We write 0 to DP_LINK_BW_SET (DPCD 100h) even when using
DP_LINK_RATE_SET (DPCD 114h). Stop doing that, as it can cause the panel
to ignore the rate set method.
Moreover, 0 is a reserved value for DP_LINK_BW_SET, and should not be
used.
v2: Improve the comments (Ville)
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9081
Tested-by: Animesh Manna <animesh.manna@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231205180551.2476228-1-jani.nikula@intel.com
Track DP enhanced framing properly in the crtc state instead
of relying just on the cached DPCD everywhere, and hook it
up into the state check and dump.
v2: Actually set enhanced_framing in .compute_config()
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230503113659.16305-1-ville.syrjala@linux.intel.com
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
The debug print for enabling SDP CRC16 is applicable only for DP2.0, but
this debug print was not within the uhbr check and was always printed.
Fix this by adding proper checks and returning.
v2: Fix typo in commit message (Ankit)
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230808042000.3210715-1-arun.r.murthy@intel.com
In order to avoid flush_scheduled_work() usage, add a dedicated
workqueue in the drm_i915_private structure. In this way, we don't
need to use the system queue anymore.
This change is mostly mechanical and based on Tetsuo's original
patch[1].
v6 by Jani:
- Also create unordered_wq for mock device
Link: https://patchwork.freedesktop.org/series/114608/ [1]
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c816ebe17ef08d363981942a096a586a7658a65e.1686231190.git.jani.nikula@intel.com
"CDS interlane align done" is a passing condition not an error.
Before adding new macros for logs it was drm_dbg_kms.
Fixes: f48eab2902 ("drm/i915/dp: Add link training debug and error printing helpers")
Cc: Imre Deak <imre.deak@intel.com>
CC: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606224428.3791006-1-khaled.almahallawy@intel.com
Prevent downgrading the link training maximum lane count/rate if the
sink is disconnected - and so the link training failure is expected. In
such cases modeset failures due to the reduced max link params would be
just confusing for user space (instead of which the correct thing it
should act on is the sink disconnect signaled by a hotplug event,
requiring a disabling modeset).
v2:
- Check the actual HPD state to handle the forced connector state case.
(Vinod)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1)
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510103131.1618266-11-imre.deak@intel.com
If a sink is disconnected it's expected that link training actions will
fail on it, so downgrade the error messages about such actions to be a
debug message. Such - expected - link training failures are more
frequent after a follow up patch, after which an active TypeC link is
reset after the sink is disconnected which also involves a link
training.
v2:
- Check the actual HPD state to handle the forced connector state case.
(Vinod)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1)
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510103131.1618266-10-imre.deak@intel.com
Add functions for printing link training debug and error messages, both
to prepare for the next patch, which downgrades an error to a debug
message if the sink is disconnected and to remove some code duplication.
v2: (Ville)
- Always print the connector prefix.
- Preserve the drm_dbg_kms() debug category.
v3:
- Keep printing the name of functions calling the helpers. (Jani)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v2)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510103131.1618266-9-imre.deak@intel.com
For 128b/132b LT prior to LT DPTX should set power state, DP channel
coding and then link rate.
v2: added separate function to avoid code duplication(Jani N)
v3: DP2.1 section 3.5.2.16 is ordered, 3.5.1.2 is unordered and hence
discarding <Ville>
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230425025944.151744-1-arun.r.murthy@intel.com
Move VRR enabling/disabling into a place where it also works
for fastsets.
With this we always start the transcoder up in non-VRR mode.
Granted we already did that but for a very short period of
time. But now that we might end up doing a bit more with the
transcoder in non-VRR mode it seems prudent to also update
the active timings as the transcoder changes its operating
mode.
crtc_state->vrr.enable still tracks whether VRR is actually
enabled or not, but now we configure all the other VRR timing
registers whenever VRR is possible (whether we actually enable
it or not). crtc_state->vrr.flipline can now serve as our
"is VRR possible" bit of state.
I decided to leave the MSA timing ignore bit set all the time
whether VRR is actually enabled or not. If the sink can figure
out the timings with that information when VRR is active then
surely it can also do it when VRR is inactive.
v2: Protect intel_vrr_set_transcoder_timings() with HAS_VRR()
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230321135615.27338-1-ville.syrjala@linux.intel.com
Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Enable SDP error detection configuration, this will set CRC16 in
128b/132b link layer.
For Display version 13 a hardware bit31 in register VIDEO_DIP_CTL is
added to enable/disable SDP CRC applicable for DP2.0 only, but the
default value of this bit will enable CRC16 in 128b/132b hence
skipping this write.
Corrective actions on SDP corruption is yet to be defined.
v2: Moved the CRC enable to link training init(Jani N)
v3: Moved crc enable to ddi pre enable <Jani N>
v4: Separate function for SDP CRC16 (Jani N)
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230302081532.765821-3-arun.r.murthy@intel.com
If the ignore long HPD flag is set, ignore the link training
failures as well. Because of spurious HPDs, some unexpected link
training failures are happening while executing IGT test cases.
Ignore the link training failures for the time being if the long
HPDs are also ignored in the environments like CI.
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230215083832.287519-3-vinod.govindapillai@intel.com
Bspec calls us to select pattern 2 after link training for
DP 2.0. Let's do that... by doing nothing because we will
be transmitting pattern 2 at the end of the link training
already.
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230308212627.7601-2-ville.syrjala@linux.intel.com
Drop the local intel_dp_phy_name() function, and replace with
drm_dp_phy_name(). This lets us drop a number of local buffers.
v2: Rebase
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220912132313.2774603-1-jani.nikula@intel.com
A lot of modern laptops use the Parade PS8461E MUX for eDP
switching. The MUX can operate in jitter cleaning mode or
redriver mode, the first one resulting in higher link
quality. The jitter cleaning mode needs to know the link
rate used and the MUX achieves this by snooping the
LINK_BW_SET, LINK_RATE_SELECT and SUPPORTED_LINK_RATES
DPCD accesses.
When the MUX is powered down (seems this can happen whenever
the display is turned off) it loses track of the snooped
link rates so when we do the LINK_RATE_SELECT write it no
longer knowns which link rate we're selecting, and thus it
falls back to the lower quality redriver mode. This results
in unstable high link rates (eg. usually 8.1Gbps link rate
no longer works correctly).
In order to avoid all that let's re-snoop SUPPORTED_LINK_RATES
from the sink at the start of every link training.
Unfortunately we don't have a way to detect the presence of
the MUX. It looks like the set of laptops equipped with this
MUX is fairly large and contains devices from multiple
manufacturers. It may also still be growing with new models.
So a quirk doesn't seem like a very easily maintainable
option, thus we shall attempt to do this unconditionally on
all machines that use LINK_RATE_SELECT. Hopefully this extra
DPCD read doesn't cause issues for any unaffected machine.
If that turns out to be the case we'll need to convert this
into a quirk in the future.
Cc: stable@vger.kernel.org
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6205
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220902070319.15395-1-ville.syrjala@linux.intel.com
Tested-by: Aaron Ma <aaron.ma@canonical.com>
Tested-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
To avoid AUX timeouts and subsequent spurious hotplug interrupts, make
sure that the first DPCD access during detection is a read from an LTTPR
register.
Some ADLP DP link configuration at least with multiple LTTPRs expects
the first DPCD access during the LTTPR/DPCD detection after hotplug to
be a read from the LTTPR range starting with
DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV. The side effect of
this read is to put each LTTPR into the LTTPR transparent or LTTPR
non-transparent mode.
The lack of the above read may leave some of the LTTPRs in non-LTTPR
mode, while other LTTPRs in LTTPR transparent or LTTPR non-transparent
mode (for instance LTTPRs after system suspend/resume that kept their
mode from before suspend). Due to the different AUX timeouts the
different modes imply, the DPCD access from a non-LTTPR range will
timeout and lead to an LTTPR generated hotplug towards the source (which
the LTTPR firmware uses to account for buggy TypeC adapters with a long
wake-up delay).
SYSCROS: 72939
v2: Keep DPCD read-out working on non-LTTPR platforms.
v3: Summarize what and why the patch does at the beginning of the commit
log. (Jani)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220408224629.845887-1-imre.deak@intel.com
At least some DELL monitors (P2715Q) with DPCD_REV 1.2 return corrupted
DPCD register values when reading from the 0xF0000- LTTPR range with an
AUX transaction block size bigger than 1. The DP standard requires 0 to
be returned - as for any other reserved/invalid addresses - but these
monitors return the DPCD_REV register value repeated in each byte of the
read buffer. This will in turn corrupt the values returned by the LTTPRs
between the source and the monitor: LTTPRs must adjust the values they
read from the downstream DPRX, for instance right-shift/init the
downstream DP_PHY_REPEATER_CNT value. Since the value returned by the
monitor's DPRX is non-zero the adjusted values will be corrupt.
Reading the LTTPR registers one-by-one instead of reading all of them
with a single AUX transfer works around the issue.
According to the DP standard's 0xF0000 register description:
"LTTPR-related registers at DPCD Addresses F0000h through F02FFh are
valid only for DPCD r1.4 (or higher)." While it's unclear if DPCD r1.4
refers to the DPCD_REV or to the
LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV register (tickets filed
at the VESA site to clarify this haven't been addressed), one
possibility is that it's a restriction due to non-compliant monitors
described above. Disabling the non-transparent LTTPR mode for all such
monitors is not a viable solution: the transparent LTTPR mode has its
own issue causing link training failures and this would affect a lot of
monitors in use with DPCD_REV < 1.4. Instead this patch works around
the problem by reading the LTTPR common and PHY cap registers one-by-one
for any monitor with a DPCD_REV < 1.4.
The standard requires the DPCD capabilities to be read after the LTTPR
common capabilities are read, so re-read the DPCD capabilities after
the LTTPR common and PHY caps were read out.
v2:
- Use for instead of a while loop. (Ville)
- Add to code comment the monitor model with the problem.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4531
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220322143844.42616-1-imre.deak@intel.com
The DP 2.0 errata completely overhauls the 128b/132b link training, with
no provisions for backward compatibility with the original DP 2.0
specification.
The changes are too intrusive to consider reusing the same code for both
8b/10b and 128b/132b, mainly because the LTTPR channel equalisation is
done concurrently instead of serialized.
NOTES:
* It's a bit unclear when to wait for DP_INTERLANE_ALIGN_DONE and
per-lane DP_LANE_SYMBOL_LOCKED. Figure xx4 in the SCR implies the
LANEx_CHANNEL_EQ_DONE sequence may end with either 0x77,0x77,0x85 *or*
0x33,0x33,0x84 (for four lane configuration in DPCD 0x202..0x204)
i.e. without the above bits set. Text elsewhere seems contradictory or
incomplete.
* We read entire link status (6 bytes) everywhere instead of individual
DPCD addresses.
* There are some subtle ambiguities or contradictions in the order of
some DPCD access and TPS signal enables/disables. It's also not clear
whether these are significant.
v4:
- Wait for intra-hop clear after link training end (Ville)
- Wait instead of single check for intra-hop clear before link train
v3:
- Use msecs_to_jiffies_timeout() (Ville)
- Read status at the beginning of interlane align done loop (Ville)
- Try to simplify timeout flag use where possible (Ville)
v2:
- Always try one last time after timeouts to avoid races (Ville)
- Extend timeout to cover the entire LANEx_EQ_DONE sequence (Ville)
- Also check for eq interlane align done in LANEx_CDS_DONE Sequence (Ville)
- Check for Intra-hop status before link training
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220208143209.2997337-1-jani.nikula@intel.com
Use the new link training delay helpers, fixing the delays for
128b/132b.
For existing 8b/10b functionality, this will cause additional 1-byte
DPCD reads for LTTPR delays instead of using the cached values. It's
just too complicated to combine generic helpers with local caching in a
sensible way.
Cc: Ville Syrjälä <ville.syrjala@linux.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/20211014150059.28957-3-jani.nikula@intel.com
The 128b/132b channel coding link training uses more straightforward TX
FFE preset values. Reuse voltage tries and max vswing for retry logic.
The delays for 128b/132b are still all wrong, but this is regardless a
step forward.
v2: Fix UHBR rate checks, use intel_dp_is_uhbr() helper
v3:
- Rebase
- Modify intel_dp_adjust_request_changed() and
intel_dp_link_max_vswing_reached() to take 128b/132b into
account. (Ville)
v4:
- Train request printing for TX FFE (Ville)
- Log 8b/10b vs. 128b/132b (Ville)
- Add helper for per-lane max vswing / tx ffe (Ville)
- Name functions with tx_ffe/vswing instead of 128b132b/8b10b
Cc: Ville Syrjälä <ville.syrjala@linux.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/20211011182144.22074-2-jani.nikula@intel.com
