The symbol is not used outside of the file, so mark it static.
Fixes the following warning:
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn32/dcn32_mmhubbub.c:214:28:
warning: symbol 'dcn32_mmhubbub_funcs' was
not declared. Should it be static?
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
These symbols qp_table_422_10bpc_min, qp_table_444_8bpc_max,
qp_table_420_12bpc_max, qp_table_444_10bpc_min, qp_table_420_8bpc_max,
qp_table_444_8bpc_min, qp_table_444_12bpc_min, qp_table_420_12bpc_min,
qp_table_422_12bpc_min, qp_table_422_12bpc_max, qp_table_444_12bpc_max,
qp_table_420_8bpc_min, qp_table_422_8bpc_min, qp_table_422_10bpc_max,
qp_table_420_10bpc_max, qp_table_420_10bpc_min, qp_table_444_10bpc_max,
qp_table_422_8bpc_max are not used outside of the file,
so mark them static.
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:28:18: warning:
symbol 'qp_table_422_10bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:61:18: warning:
symbol 'qp_table_444_8bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:102:18: warning:
symbol 'qp_table_420_12bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:135:18: warning:
symbol 'qp_table_444_10bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:188:18: warning:
symbol 'qp_table_420_8bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:209:18: warning:
symbol 'qp_table_444_8bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:250:18: warning:
symbol 'qp_table_444_12bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:315:18: warning:
symbol 'qp_table_420_12bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:348:18: warning:
symbol 'qp_table_422_12bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:389:18: warning:
symbol 'qp_table_422_12bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:430:18: warning:
symbol 'qp_table_444_12bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:495:18: warning:
symbol 'qp_table_420_8bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:516:18: warning:
symbol 'qp_table_422_8bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:541:18: warning:
symbol 'qp_table_422_10bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:574:16: warning:
symbol 'qp_table_420_10bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:601:18: warning:
symbol 'qp_table_420_10bpc_min' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:628:18: warning:
symbol 'qp_table_444_10bpc_max' was not declared. Should it be static?
./drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dsc/qp_tables.h:681:18: warning:
symbol 'qp_table_422_8bpc_max' was not declared. Should it be static?
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Commit 8795e182b0 ("PCI/portdrv: Don't disable AER reporting in get_port_device_capability()")
uncovered a bug in amdgpu that required a reordering of the driver
init sequence to avoid accessing a special register on the GPU
before it was properly set up leading to an PCI AER error. This
reordering uncovered a different hw programming ordering dependency
in some APUs where the SDMA doorbells need to be programmed before
the GFX doorbells. To fix this, move the SDMA doorbell programming
back into the soc15 common code, but use the actual doorbell range
values directly rather than the values stored in the ring structure
since those will not be initialized at this point.
This is a partial revert, but with the doorbell assignment
fixed so the proper doorbell index is set before it's used.
Fixes: e3163bc8ff ("drm/amdgpu: move nbio sdma_doorbell_range() into sdma code for vega")
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: skhan@linuxfoundation.org
When using a device based on DCN32/321,
we have an issue where a second
4k@60Hz display does not light up,
and the system becomes unresponsive
for a few minutes. In the debug process,
it was possible to see a hang
in the function dcn20_post_unlock_program_front_end
in this part:
for (j = 0; j < TIMEOUT_FOR_PIPE_ENABLE_MS*1000
&& hubp->funcs->hubp_is_flip_pending(hubp); j++)
mdelay(1);
}
The hubp_is_flip_pending always returns positive
for waiting pending flips which is a symptom of
pipe hang. Additionally, the dmesg log shows
this message after a few minutes:
BUG: soft lockup - CPU#4 stuck for 26s!
...
[ +0.000003] dcn20_post_unlock_program_front_end+0x112/0x340 [amdgpu]
[ +0.000171] dc_commit_state_no_check+0x63d/0xbf0 [amdgpu]
[ +0.000155] ? dc_validate_global_state+0x358/0x3d0 [amdgpu]
[ +0.000154] dc_commit_state+0xe2/0xf0 [amdgpu]
This confirmed the hypothesis that we had a pipe
hanging somewhere. Next, after checking the
ftrace entries, we have the below weird
sequence:
[..]
2) | dcn10_lock_all_pipes [amdgpu]() {
2) 0.120 us | optc1_is_tg_enabled [amdgpu]();
2) | dcn20_pipe_control_lock [amdgpu]() {
2) | dc_dmub_srv_clear_inbox0_ack [amdgpu]() {
2) 0.121 us | amdgpu_dm_dmub_reg_write [amdgpu]();
2) 0.551 us | }
2) | dc_dmub_srv_send_inbox0_cmd [amdgpu]() {
2) 0.110 us | amdgpu_dm_dmub_reg_write [amdgpu]();
2) 0.511 us | }
2) | dc_dmub_srv_wait_for_inbox0_ack [amdgpu]() {
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
2) 0.110 us | amdgpu_dm_dmub_reg_read [amdgpu]();
[..]
We are not expected to read from dmub register
so many times and for so long. From the trace log,
it was possible to identify that the function
dcn20_pipe_control_lock was triggering the dmub
operation when it was unnecessary and causing
the hang issue. This commit drops the unnecessary
dmub code and, consequently, fixes the second display not
lighting up the issue.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Sub-viewport (Subvp) feature is used for changing MCLK without causing
any display artifact, requiring special treatment from the plane and
stream perspective since DC needs to read data from the cache when using
subvp. However, the function dc_commit_updates_for_stream does not
provide all the support needed by this feature which will make this
function legacy at some point. For this reason, this commit enables
dc_update_planes_and_stream for ASICs that support this feature but
preserves the old behavior for other ASICs. However,
dc_update_planes_and_stream should replace dc_commit_updates_for_stream
for all ASICs since it does most of the tasks executed by
dc_commit_updates_for_stream with other extra operations, but we need to
run tests before making this change.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
OTG instance is not updated in dc_commit_state_no_check for newly
committed streams because mode_change is not set. Notice that OTG update
is part of the software state, and after hardware programming, it must
be updated; for this reason, this commit updates the OTG offset right
after hardware programming.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
A seamless boot stream has hardware resources assigned to it, and adding
a new stream means rebuilding the current assignment. It is desirable to
avoid this situation since it may cause light-up issues on the VGA
monitor on USB-C. This commit swaps the seamless boot stream to pipe 0
(if necessary) to ensure that the pipe context matches.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
DC stream can be seen as a representation of the DCN backend or the data
struct that represents the center of the display pipeline. The front end
(i.e., planes) is connected to the DC stream, and in its turn, streams
are connected to the DC link. Due to this dynamic, DC must handle the
following scenarios:
1. A stream is removed;
2. A new stream is created;
3. An unchanged stream had some updates on its planes.
These combinations require that the new stream data struct become
updated and has a valid global state. For handling multiple corner cases
associated with stream operations, this commit introduces a function
dedicated to manipulating stream changes and invokes the state
validation function after that.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
The commit stream function does not include surfaces of unaffected
streams, which may lead to some blank screens during mode change in some
edge cases. This commit adds surfaces of unaffected streams followed by
kernel-doc for documenting some of the fields that participate in this
change.
v2: squash in kerneldoc warning fix (Alex)
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
DC adds an instance of DML (which contains VBA) to each context, and
multiple threads might write back to the global VBA resulting in data
overwriting. To keep the consistency with other parts of the DC code,
this commit changes dc_commit_streams to copy the current DC state, and
as a result, it also changes the function signature to expect streams
instead of a context.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Change commit sequence will impact all ASICs. It is prudent to run this
update in small steps to keep issues under control and avoid any
potential regression. With this idea in mind, this commit is preparation
work for the complete transition to the new commit sequence. To maintain
this change manageable across multiple ASICs, this commit adds a new
function named dc_commit_streams which is a copy of the dc_commit_state
with some minor changes. Finally, inside the dc_commit_state, we check
if we are using DCN32x or above and enable the new sequence only for
those devices.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Context change is all about streams; for this reason, this commit
renames context_changed to streams_changed. Additionally, to make this
function more flexible, this commit changes the function signature to
receive the stream array and the stream count as a parameter.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
If the number of pages from the userptr BO differs from the SG BO then the
allocated memory for the SG table doesn't get freed before returning
-EINVAL, which may lead to a memory leak in some error paths. Fix this by
checking the number of pages before allocating memory for the SG table.
Fixes: 264fb4d332 ("drm/amdgpu: Add multi-GPU DMA mapping helpers")
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
MMHUB 2.1.x versions don't have ATCL2. Remove accesses to ATCL2 registers.
Since they are non-existing registers, read access will cause a
'Completer Abort' and gets reported when AER is enabled with the below patch.
Tagging with the patch so that this is backported along with it.
v2: squash in uninitialized warning fix (Nathan Chancellor)
Fixes: 8795e182b0 ("PCI/portdrv: Don't disable AER reporting in get_port_device_capability()")
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
DGFX platforms has lmem and cpu can access the lmem objects
via mmap and i915 internal i915_gem_object_pin_map() for
i915 own usages. Both of these methods has pre-requisite
requirement to keep GFX PCI endpoint in D0 for a supported
iomem transaction over PCI link. (Refer PCIe specs 5.3.1.4.1)
Both DG1/DG2 have a known hardware bug that violates the PCIe specs
and support the iomem read write transaction over PCIe bus despite
endpoint is D3 state.
Due to above H/W bug, we had never observed any issue with i915 runtime
PM versus lmem access.
But this issue becomes visible when PCIe gfx endpoint's upstream
bridge enters to D3, at this point any lmem read/write access will be
returned as unsupported request. But again this issue is not observed
on every platform because it has been observed on few host machines
DG1/DG2 endpoint's upstream bridge does not bind with pcieport driver.
which really disables the PCIe power savings and leaves the bridge
at D0 state.
We need a unique interface to read/write from lmem with runtime PM
wakeref protection something similar to intel_uncore_{read, write},
keep autosuspend control to 'on' on all discrete platforms,
until we have a unique interface to read/write from lmem.
This just change the default autosuspend setting of i915 on dGPU,
user can still change it to 'auto'.
v2:
- Modified the commit message and subject with more information.
- Changed the Fixes tag to LMEM support commit. [Joonas]
- Changed !HAS_LMEM() Cond to !IS_DGFX(). [Rodrigo]
Fixes: b908be543e ("drm/i915: support creating LMEM objects")
Suggested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014113258.1284226-1-anshuman.gupta@intel.com
(cherry picked from commit 66eb93e71a)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Originally, the it6505 relies on a short sleep in the IRQ handler and a
long sleep to make sure it6505->lane_swap and it6505->lane_count is
configured in it6505_extcon_work and it6505_detect, respectively.
Use completion and additional DPCD read to remove the unnecessary waits,
and use a different lock for it6505_extcon_work and the threaded IRQ
handler because they no longer need to run exclusively.
The wait time of the completion is usually less than 10ms in local
experiments, but leave it larger here just in case.
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013110411.1674359-4-treapking@chromium.org
Be consistent in whether we flag a full modeset or a
fastset for the pipe. intel_modeset_all_pipes() would
seem to be the only codepath not getting this right.
The other case is when we flag the fastset initially,
currently we just clear the mode_changed flag and set
the update_pipe flag. But we could still have
connectors_changed==true or active_changed==true forcing
a full modeset anyway. So check for that after clearing
the mode_changed flag.
And let's add a WARN to make sure we did get it right.
v2: Deal with {connectors,active}_changed
Reviewed-by: Jani Nikula <jani.nikula@intel.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221021162442.27283-4-ville.syrjala@linux.intel.com
On BDW+ we have just the one set of DP M/N registers. The
values we write into said registers depends on whether we
want DRRS to be in high or low gear. This causes issues
for the state checker which currently has to assume either
set of M/N (high or low refresh rate) values may appear there.
That sort of works for M/N itself, but all other values
derived from the M/N (dotclock, pixel rate) are not handled
correctly, leading to potential for state checker mismatches.
Let's avoid all those problems by simply keeping DRRS in
high gear until the state checker has done its hardware
state readout.
Note that hitting this issue presumable became very hard
after commit 1b333c679a ("drm/i915: Do DRRS disable/enable
during pre/post_plane_update()") since the state check would
have to laze about for one full second (delay used by
intel_drrs_schedule_work()) to see the low refresh rate.
But it is still theoretically possible.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221020120706.25728-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
[why]
MES response time in sriov may be longer than default value
due to reset or init in other VF. A timeout value specific
to sriov is needed.
[how]
When in sriov, adjust the timeout value to calculated
worst case scenario.
Signed-off-by: Yiqing Yao <yiqing.yao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[WHY]
0, original pstate X
1, ctx_A_create -> ctx_A->stable_pstate = X
2, ctx_A_set_pstate (Y) -> current pstate is Y (PEAK or STANDARD)
3, ctx_B_create -> ctx_B->stable_pstate = Y
4, ctx_A_destroy -> restore pstate to X
5, ctx_B_destroy -> restore pstate to Y
Above sequence will cause final pstate is wrong (Y), should be original X.
[HOW]
When ctx_B create,
if ctx_A touched pstate setting
(not auto, stable_pstate_ctx != NULL),
set ctx_B->stable_pstate the same value as ctx_A saved,
if stable_pstate_ctx == NULL,
fetch current pstate to fill
ctx_B->stable_pstate.
Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
[why]
MES response time in sriov may be longer than default value
due to reset or init in other VF. A timeout value specific
to sriov is needed.
[how]
When in sriov, adjust the timeout value to calculated
worst case scenario.
Signed-off-by: Yiqing Yao <yiqing.yao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[WHY]
0, original pstate X
1, ctx_A_create -> ctx_A->stable_pstate = X
2, ctx_A_set_pstate (Y) -> current pstate is Y (PEAK or STANDARD)
3, ctx_B_create -> ctx_B->stable_pstate = Y
4, ctx_A_destroy -> restore pstate to X
5, ctx_B_destroy -> restore pstate to Y
Above sequence will cause final pstate is wrong (Y), should be original X.
[HOW]
When ctx_B create,
if ctx_A touched pstate setting
(not auto, stable_pstate_ctx != NULL),
set ctx_B->stable_pstate the same value as ctx_A saved,
if stable_pstate_ctx == NULL,
fetch current pstate to fill
ctx_B->stable_pstate.
Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Pull misc fixes from Andrew Morron:
"Seventeen hotfixes, mainly for MM.
Five are cc:stable and the remainder address post-6.0 issues"
* tag 'mm-hotfixes-stable-2022-10-20' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
nouveau: fix migrate_to_ram() for faulting page
mm/huge_memory: do not clobber swp_entry_t during THP split
hugetlb: fix memory leak associated with vma_lock structure
mm/page_alloc: reduce potential fragmentation in make_alloc_exact()
mm: /proc/pid/smaps_rollup: fix maple tree search
mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages
mm/mmap: fix MAP_FIXED address return on VMA merge
mm/mmap.c: __vma_adjust(): suppress uninitialized var warning
mm/mmap: undo ->mmap() when mas_preallocate() fails
init: Kconfig: fix spelling mistake "satify" -> "satisfy"
ocfs2: clear dinode links count in case of error
ocfs2: fix BUG when iput after ocfs2_mknod fails
gcov: support GCC 12.1 and newer compilers
zsmalloc: zs_destroy_pool: add size_class NULL check
mm/mempolicy: fix mbind_range() arguments to vma_merge()
mailmap: update email for Qais Yousef
mailmap: update Dan Carpenter's email address
Back in commit 826cff3f7e ("drm/bridge: parade-ps8640: Enable
runtime power management") we removed a mysterious 50 ms delay because
"Parade's support [couldn't] explain what the delay [was] for".
While I'm always a fan of removing mysterious delays, I suspect that
we need this mysterious delay to avoid some problems.
Specifically, what I found recently is that on sc7180-trogdor-homestar
sometimes the AUX backlight wasn't initializing properly. Some
debugging showed that the drm_dp_dpcd_read() function that the AUX
backlight driver was calling was returning bogus data about 1% of the
time when I booted up. This confused
drm_panel_dp_aux_backlight(). From continued debugging:
- If I retried the read then the read worked just fine.
- If I added a loop to perform the same read that
drm_panel_dp_aux_backlight() was doing 30 times at bootup I could
see that some percentage of the time the first read would give bogus
data but all 29 additional reads would always be fine.
- If I added a large delay _after_ powering on the panel but before
powering on PS8640 I could still reproduce the problem.
- If I added a delay after PS8640 powered on then I couldn't reproduce
the problem.
- I couldn't reproduce the problem on a board with the same panel but
the ti-sn65dsi86 bridge chip.
To me, the above indicated that there was a problem with PS8640 and
not the panel.
I don't really have any insight into what's going on in the MCU, but
my best guess is that when the MCU itself sees the HPD go high that it
does some AUX transfers itself and this is confusing things.
Let's go back and add back in the mysterious 50 ms delay. We only want
to do this the first time we see HPD go high after booting the MCU,
not every time we double-check HPD.
With this, the backlight initializes reliably on homestar.
Fixes: 826cff3f7e ("drm/bridge: parade-ps8640: Enable runtime power management")
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221017121813.1.I59700c745fbc31559a5d5c8e2a960279c751dbd5@changeid
