drm/amd/display: Fix 2nd DPIA encoder Assignment

[HOW & Why]
There seems to be an issue with 2nd DPIA acquiring link encoder for tiled displays.
Solution is to remove check for eng_id before we get first dynamic encoder for it

Reviewed-by: Cruise Hung <cruise.hung@amd.com>
Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Add DPIA Link Encoder Assignment Fix

For DPIA we should have preferred DIG assignment based on DPIA selected
as per the ASIC design.

Reviewed-by: George Shen <george.shen@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix 2nd DPIA encoder Assignment

[HOW & Why]
There seems to be an issue with 2nd DPIA acquiring link encoder for tiled displays.
Solution is to remove check for eng_id before we get first dynamic encoder for it

Reviewed-by: Cruise Hung <cruise.hung@amd.com>
Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Add DPIA Link Encoder Assignment Fix

For DPIA we should have preferred DIG assignment based on DPIA selected
as per the ASIC design.

Reviewed-by: George Shen <george.shen@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drm/amd/display: remove unused matching_stream_ptrs variable

clang with W=1 reports
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_enc_cfg.c:625:6: error:
variable 'matching_stream_ptrs' set but not used [-Werror,-Wunused-but-set-variable]
int matching_stream_ptrs = 0;
^
This variable is not used so remove it.

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: convert link.h functions to function pointer style

[Why & How]
All dc subcomponents should call another dc component via function pointers
stored in a component structure. This is part of dc coding convention since
the beginning. The reason behind this is to improve encapsulation and
polymorphism. The function contract is extracted into a single link service
structure defined in link.h header file and implemented only in link_factory.c instead
of spreading across multiple files in link component file structure.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: merge dc_link_dp into dc_link

[why]
Temporarly merge dc_link_dp functions into dc_link for the
purpose of removing dc_link_dp files. This is a transitional
change for later commits where we will further refactor dc_link
file.

Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: move dp capability related logic to link_dp_capability

Tested-by: Daniel Wheeler <Daniel.Wheeler@amd.com>
Reviewed-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix DPIA link encoder assignment issue

[Why]
The DPIA link encoder (DIG) was not released when a Display XDR 6K
monitor was disconnected. That's because the DPIA link encoder logic
checked the BW when it removed the link encoder for it. And the timing
BW was less than DP link BW. So, it failed to release the link encoder.
And that caused the DIG was occupied and can't be used. The reason it
checked the BW is it wants to identify whether this link was using DIG
or HPO. It skips if it's not DIG.

[How]
Not to check the BW when it removes the link encoder because it's
already in the assignment table, it must be the DIG.

Tested-by: Daniel Wheeler <Daniel.Wheeler@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Cruise Hung <Cruise.Hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Maintain consistent mode of operation during encoder assignment

[Why]
While applying a state to hardware, there is a transition period where
the back-end is reset using the old state; then enabled using the new
state.

Generally, the link encoder configuration module queries
stream-to-encoder assignments in either the new or old state based on a
mode variable. During the transition there is a need to query both
states, however toggling this mode variable can lead to incorrect
programming of encoders.

[How]
- Add new function to explicity query stream-to-encoder assignment
in the current state rather than intermittently switch the mode
of operation of the link encoder assignment module.
- Add additional checks for encoder assignment defects.
- Explicitly reset the mode of operation if application of state
to hardware ends prematurely.

Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix entry into transient encoder assignment mode.

[Why]
In some scenarios it is possible for the encoder assignment module to be
set to "transient" mode even though there are no new encoder
assignments.

This can lead to incorrect results when querying encoder assignment,
which in turn can cause incorrect displays to be manipulated.

[How]
Only allow encoder assignment to be in transient mode of operation when
there are valid new encoder assignments.

Reviewed-by: Meenakshikumar Somasundaram <Meenakshikumar.Somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix double free during GPU reset on DC streams

[Why]
The issue only occurs during the GPU reset code path.

We first backup the current state prior to commiting 0 streams
internally from DM to DC. This state backup contains valid link
encoder assignments.

DC will clear the link encoder assignments as part of current state
(but not the backup, since it was a copied before the commit) and
free the extra stream reference it held.

DC requires that the link encoder assignments remain cleared/invalid
prior to commiting. Since the backup still has valid assignments we
call the interface post reset to clear them. This routine also
releases the extra reference that the link encoder interface held -
resulting in a double free (and eventually a NULL pointer dereference).

[How]
We'll have to do a full DC commit anyway after GPU reset because
the stream count previously went to 0.

We don't need to retain the assignment that we had backed up, so
just copy off of the now clean current state assignment after the
reset has occcurred with the new link_enc_cfg_copy() interface.

Fixes: 6d63fcc2a334 ("drm/amd/display: Reset link encoder assignments for GPU reset")

Reviewed-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Call dc_stream_release for remove link enc assignment

[Why]
A porting error resulted in the stream assignment for the link
being retained without being released - a memory leak.

[How]
Fix the porting error by adding back the dc_stream_release() intended
as part of the original patch.

Fixes: 0bb245558584 ("drm/amd/display: retain/release at proper places in link_enc assignment")

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: add protection in link encoder matching logic

[Why]
Link encoders are created based on its engine ID. The position of a link
encoder in an array could be null since it didn't be allocated. Current
matching logic didn't consider this situation and could get null
encoder.

[How]
To add null encoder check to make the matching logic can go to next to
get a valid one.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Martin Tsai <martin.tsai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: retain/release at proper places in link_enc assignment

[why]
Need to keep track of number of
references to stream pointer.

[how]
Call stream retain/release whenever
necessary in link_enc table assignment
sequence.

Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Revert "retain/release stream pointer in link enc table"

[why]
Change causing issue. Need to revert the change.

Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Initialise encoder assignment when initialising dc_state

[Why]
Link encoder assignment tracking variables need to be (re)initialised
whenever dc_state is (re)initialised. Otherwise variables used for
dynamic encoder assignment (especially the link encoder availability
pool) are out of sync with dc_state and future encoder assignments are
invalid.

[How]
Initialise encoder assignment variables when creating new dc_state
resource.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Query all entries in assignment table during updates.

[Why]
Stream ordering and count can vary from one state to the next. Only
checking a subset of entries in the encoder assignment table can lead to
invalid encoder assignments.

[How]
Check all entries in encoder assignment table when querying it.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: retain/release stream pointer in link enc table

[why]
At every reference to stream pointer, we need to increment/decrement the
kref_count. Not doing so will result in invalid stream pointer still
alive after hibernate cycle.

[how]
Call stream retain/release whenever the link encoder assignment is set
to true/false since it indicates if we want to reference the stream
pointer or not.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: fix stale info in link encoder assignment

[Why]
The link encoder assignment leaves the old stream data when it was
unassigned. When the clear encoder assignment is called, it based on the
old stale data to access the de-allocated stream.

[How]
There should be no need to explicitly clean up the link encoder
assignment if the unassign loop does the work properly, the loop should
base on the current state to clean up the assignment.

Also, the unassignment should better clean up the values in the
assignement slots as well.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Roy Chan <roy.chan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Clear encoder assignments when state cleared.

[Why]
State can be cleared without removing individual streams (by
calling dc_remove_stream_from_ctx()). This can leave the
encoder assignment module in an incoherent state and cause
future assignments to be incorrect.

[How]
Clear encoder assignments when committing 0 streams or
re-initializing hardware.

Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Do not skip link training on DP quick hot plug

[Why]
When rapidly plugging and unplugging a DP sink, detection link
training can be mistakenly skipped.

This is due to the hotplug processing occurring before the
encoder assignment logic has had a chance to process the removal
of a stream. The encoder that would be used for detection link
training is then erroneously reported as already in use and
detection link training is skipped.

[How]
During hot plug processing, only determine a link encoder to be
unavailable for a particular link if it has been assigned to a
different link.

Reviewed-by: Meenakshikumar Somasundaram <Meenakshikumar.Somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix MST link encoder availability check.

[Why]
MST streams share the same link and should share the same encoder.
The current availability check may erroneously determine that an
encoder is unavailable for MST streams.

[How]
When checking for link encoder availability, check if an encoder
in use shares a link with the stream for which the availability
check is being conducted. If the link is shared, then the link
encoder should be shared too and will be deemed available.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix dynamic encoder reassignment

[Why]
Incorrect encoder assignments were being used while applying a new state
to hardware.

(1) When committing a new state to hardware requires resetting the
back-end, the encoder assignments of the current or old state should be
used when disabling the back-end; and the encoder assignments for the
next or new state should be used when re-enabling the back-end.

(2) Link training on hot plug could take over an encoder already in use
by another stream without first disabling it.

[How]

(1) Introduce a resource context 'link_enc_cfg_context' which includes:
- a mode to indicate when transitioning from current to next state.
- transient encoder assignments to use during this state transition.

Update the encoder configuration interface to respond to queries about
encoder assignment based on the mode of operation.

(2) Check if an encoder is already in use before attempting to perform
link training on hot plug.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix concurrent dynamic encoder assignment

[Why]
Trying to enable multiple displays simultaneously exposed shortcomings
with the algorithm for dynamic link encoder assignment.

The main problems were:
- Assuming stream order remained constant across states would sometimes
lead to invalid DIG encoder assignment.
- Incorrect logic for deciding whether or not a DIG could support a
stream would also sometimes lead to invalid DIG encoder assignment.
- Changes in encoder assignment were wholesale while updating of the
pipe backend is incremental. This would lead to the hardware state not
matching the software state even with valid encoder assignments.

[How]

The following changes fix the identified problems.
- Use stream pointer rather than stream index to track streams across
states.
- Fix DIG compatibility check by examining the link signal type rather
than the stream signal type.
- Modify assignment algorithm to make incremental updates so software
and hardware states remain coherent.

Additionally:
- Add assertions and an encoder assignment validation function
link_enc_cfg_validate() to detect potential problems with encoder
assignment closer to their root cause.
- Reduce the frequency with which the assignment algorithm is executed.
It should not be necessary for fast state validation.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Fix dynamic link encoder access.

[Why]
Assuming DIG link encoders are statically mapped to links can cause
system instability due to null pointer accesses.

[How]
- Add checks for non-null link encoder pointers before trying to access
them.
- When a hardware platform uses dynamic DIG assignment (i.e. resource
function 'link_encs_assign' defined) and a link supports flexible
mapping to DIGs, use the link_enc_cfg API to access the DIG assigned to
a link or stream.

Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Remove redundant initialization of variable eng_id

The variable eng_id is being initialized with a value that is never
read, it is being re-assigned on the next statment. The assignment
is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Update setting of DP training parameters.

[Why]
Some links are dynamically assigned link encoders on stream enablement.

[How]
Update DisplayPort training parameter determination stage that assumes
link encoder statically assigned to link.

Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Update display endpoint control path.

[Why]
Some display endpoints may be dynamically mapped to the link encoders
which drive them.

[How]
Update the code paths for display enabling/disabling to accommodate
the dynamic association between links and link encoders.

Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Add dynamic link encoder selection.

[Why]
Some display endpoints may be programmably mapped to compatible link
encoders. The assignment of link encoders to links has to be dynamic to
accommodate the increased flexibility in comparison to conventional
display endpoints.

[How]
- Add link encoder assignment tracking variables.
- Execute link encoder assignment algorithm before enabling link and
release link encoders from links once they are disabled.

Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>