The self hosted claim tag will be reset on device probe in a later
commit. We'll want to do this before coresight_register() is called so
won't have a coresight_device and have to use csdev_access instead.
Also make them public and create locked and unlocked versions for
later use.
These look functions look like they set the whole tags register as one
value, but they only set and clear the self hosted bit using a SET/CLR
bits mechanism so also rename the functions to reflect this better.
Reviewed-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250325-james-coresight-claim-tags-v4-1-dfbd3822b2e5@linaro.org
The coresight_init_driver() of the coresight-core module is called from
the sub coresgiht device (such as tmc/stm/funnle/...) module. It calls
amba_driver_register() and Platform_driver_register(), which are macro
functions that use the coresight-core's module to initialize the caller's
owner field. Therefore, when the sub coresight device calls
coresight_init_driver(), an incorrect THIS_MODULE value is captured.
The sub coesgiht modules can be removed while their callbacks are
running, resulting in a general protection failure.
Add module parameter to coresight_init_driver() so can be called
with the module of the callback.
Fixes: 075b7cd7ad ("coresight: Add helpers registering/removing both AMBA and platform drivers")
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20240918035327.9710-1-hejunhao3@huawei.com
As recommended by section 4.3.7 ("Synchronization when using system
instructions to progrom the trace unit") of ARM IHI 0064H.b, the
self-hosted trace analyzer must perform a Context synchronization
event between writing to the TRCPRGCTLR and reading the TRCSTATR.
Additionally, add an ISB between the each read of TRCSTATR on
coresight_timeout() when using system instructions to program the
trace unit.
Fixes: 1ab3bb9df5 ("coresight: etm4x: Add necessary synchronization for sysreg access")
Signed-off-by: Yuanfang Zhang <quic_yuanfang@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250116-etm_sync-v4-1-39f2b05e9514@quicinc.com
Some replicators have hard coded filtering of "trace" data, based on the
source device. This is different from the trace filtering based on
TraceID, available in the standard programmable replicators. e.g.,
Qualcomm replicators have filtering based on custom trace protocol
format and is not programmable.
The source device could be connected to the replicator via intermediate
components (e.g., a funnel). Thus we need platform information from
the firmware tables to decide the source device corresponding to a
given output port from the replicator. Given this affects "trace
path building" and traversing the path back from the sink to source,
add the concept of "filtering by source" to the generic coresight
connection.
The specified source will be marked like below in the Devicetree.
test-replicator {
... ... ... ...
out-ports {
... ... ... ...
port@0 {
reg = <0>;
xyz: endpoint {
remote-endpoint = <&zyx>;
filter-source = <&source_1>; <-- To specify the source to
}; be filtered out here.
};
port@1 {
reg = <1>;
abc: endpoint {
remote-endpoint = <&cba>;
filter-source = <&source_2>; <-- To specify the source to
}; be filtered out here.
};
};
};
Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20241213100731.25914-4-quic_taozha@quicinc.com
For Perf to be able to decode when per-sink trace IDs are used, emit the
sink that's being written to for each ETM.
Perf currently errors out if it sees a newer packet version so instead
of bumping it, add a new minor version field. This can be used to
signify new versions that have backwards compatible fields. Considering
this change is only for high core count machines, it doesn't make sense
to make a breaking change for everyone.
Signed-off-by: James Clark <james.clark@arm.com>
Tested-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20240722101202.26915-17-james.clark@linaro.org
This will allow sessions with more than CORESIGHT_TRACE_IDS_MAX ETMs
as long as there are fewer than that many ETMs connected to each sink.
Each sink owns its own trace ID map, and any Perf session connecting to
that sink will allocate from it, even if the sink is currently in use by
other users. This is similar to the existing behavior where the dynamic
trace IDs are constant as long as there is any concurrent Perf session
active. It's not completely optimal because slightly more IDs will be
used than necessary, but the optimal solution involves tracking the PIDs
of each session and allocating ID maps based on the session owner. This
is difficult to do with the combination of per-thread and per-cpu modes
and some scheduling issues. The complexity of this isn't likely to worth
it because even with multiple users they'd just see a difference in the
ordering of ID allocations rather than hitting any limits (unless the
hardware does have too many ETMs connected to one sink).
Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20240722101202.26915-15-james.clark@linaro.org
At the moment the core file contains both sysfs functionality and
core functionality, while the Perf mode is in a separate file in
coresight-etm-perf.c
Many of the functions have ambiguous names like
coresight_enable_source() which actually only work in relation to the
sysfs mode. To avoid further confusion, move everything that isn't core
functionality into the sysfs file and append _sysfs to the ambiguous
functions.
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-7-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
'enable', which probably should have been 'enabled', is only ever read
in the core code in relation to controlling sources, and specifically
only sources in sysfs mode. Confusingly it's not labelled as such and
relying on it can be a source of bugs like the one fixed by
commit 078dbba3f0c9 ("coresight: Fix crash when Perf and sysfs modes are
used concurrently").
Most importantly, it can only be used when the coresight_mutex is held
which is only done when enabling and disabling paths in sysfs mode, and
not Perf mode. So to prevent its usage spreading and leaking out to
other devices, remove it.
It's use is equivalent to checking if the mode is currently sysfs, as
due to the coresight_mutex lock, mode == CS_MODE_SYSFS can only become
true or untrue when that lock is held, and when mode == CS_MODE_SYSFS
the device is both enabled and in sysfs mode.
The one place it was used outside of the core code is in TPDA, but that
pattern is more appropriately represented using refcounts inside the
device's own spinlock.
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-6-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
The check for the existence of callbacks before using them implies that
this happens and is supported. There are no devices without
enable/disable callbacks, and it wouldn't be possible to add a new
working device without adding them either, so just remove them.
Furthermore, there are more callbacks than just enable and disable that
are already used unguarded in other places.
The comment about new session compatibility doesn't seem to match up to
the line of code that it's on so remove it. I think it's alluding to the
fact that sinks will check if they were already enabled via sysfs or
Perf and fail the enable. But there are more detailed comments at those
places, and this one isn't very useful.
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-4-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Activated has the specific meaning of a sink that's selected for use by
the user via sysfs. But comments in some code that's shared by Perf use
the same word, so in those cases change them to just say "selected"
instead. With selected implying either via Perf or "activated" via
sysfs.
coresight_get_enabled_sink() doesn't actually get an enabled sink, it
only gets an activated one, so change that too.
And change the activated variable name to include "sysfs" so it can't
be confused as a general status.
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-3-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
The linked commit reverts the change that accidentally used some sysfs
enable/disable functions from Perf which broke the refcounting, but it
also removes the fact that the sysfs disable function disabled the
helpers.
Add a new wrapper function that does both which is used by both Perf and
sysfs, and label the sysfs disable function appropriately. The naming of
all of the functions will be tidied up later to avoid this happening
again.
Fixes: 287e82cf69 ("coresight: Fix crash when Perf and sysfs modes are used concurrently")
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-2-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230718143124.1065949-1-robh@kernel.org
The CTI module has some hard coded refcounting code that has a leak.
For example running perf and then trying to unload it fails:
perf record -e cs_etm// -a -- ls
rmmod coresight_cti
rmmod: ERROR: Module coresight_cti is in use
The coresight core already handles references of devices in use, so by
making CTI a normal helper device, we get working refcounting for free.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-14-james.clark@arm.com
Currently CATU is the only helper device, and its enable and disable
calls are hard coded. To allow more helper devices to be added in a
generic way, remove these hard coded calls and just enable and disable
all helper devices.
This has to apply to helpers adjacent to the path, because they will
never be in the path. CATU was already discovered in this way, so
there is no change there.
One change that is needed is for CATU to call back into ETR to allocate
the buffer. Because the enable call was previously hard coded, it was
done at a point where the buffer was already allocated, but this is no
longer the case.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-13-james.clark@arm.com
This removes the need to do an additional lookup for the total number
of ports used and also removes the need to allocate an array of
refcounts which is just another representation of a connection array.
This was only used for link type devices, for regular devices a single
refcount on the coresight device is used.
There is a both an input and output refcount in case two link type
devices are connected together so that they don't overwrite each other's
counts.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-11-james.clark@arm.com
This will allow CATU to get its associated ETR in a generic way where
currently the enable path has some hard coded searches which avoid
the need to store input connections.
This also means that the full search for connected devices on removal
can be replaced with a loop through only the input and output devices.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-10-james.clark@arm.com
There is some duplication between coresight_fixup_device_conns() and
coresight_fixup_orphan_conns(). They both do the same thing except for
the fact that coresight_fixup_orphan_conns() can't handle iterating over
itself.
By making it able to handle fixing up it's own connections the other
function can be removed.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-9-james.clark@arm.com
Add a function for adding connections dynamically. This also removes
the 1:1 mapping between port number and the index into the connections
array. The only place this mapping was used was in the warning for
duplicate output ports, which has been replaced by a search. Other
uses of the port number already use the port member variable.
Being able to dynamically add connections will allow other devices like
CTI to re-use the connection mechanism despite not having explicit
connections described in the DT.
The connections array is now no longer sparse, so child_fwnode doesn't
need to be checked as all connections have a target node. Because the
array is no longer sparse, the high in and out port numbers are required
for the refcount arrays. But these will also be removed in a later
commit when the refcount is made a property of the connection.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-7-james.clark@arm.com
child_fwnode should be a read only property based on the DT or ACPI. If
it's cleared on the parent device when a child is unloaded, then when
the child is loaded again the connection won't be remade.
child_dev should be cleared instead which signifies that the connection
should be remade when the child_fwnode registers a new coresight_device.
Similarly the reference count shouldn't be decremented as long as the
parent device exists. The correct place to drop the reference is in
coresight_release_platform_data() which is already done.
Reproducible on Juno with the following steps:
# load all coresight modules.
$ cd /sys/bus/coresight/devices/
$ echo 1 > tmc_etr0/enable_sink
$ echo 1 > etm0/enable_source
# Works fine ^
$ echo 0 > etm0/enable_source
$ rmmod coresight-funnel
$ modprobe coresight-funnel
$ echo 1 > etm0/enable_source
-bash: echo: write error: Invalid argument
Fixes: 37ea1ffddf ("coresight: Use fwnode handle instead of device names")
Fixes: 2af89ebacf ("coresight: Clear the connection field properly")
Tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-2-james.clark@arm.com
With lockdeps enabled, we get the following warning:
======================================================
WARNING: possible circular locking dependency detected
------------------------------------------------------
kworker/u12:1/53 is trying to acquire lock:
ffff80000adce220 (coresight_mutex){+.+.}-{4:4}, at: coresight_set_assoc_ectdev_mutex+0x3c/0x5c
but task is already holding lock:
ffff80000add1f60 (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (ect_mutex){+.+.}-{4:4}:
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
cti_add_assoc_to_csdev+0x4c/0x184
coresight_register+0x2f0/0x314
tmc_probe+0x33c/0x414
-> #0 (coresight_mutex){+.+.}-{4:4}:
__lock_acquire+0x1a20/0x32d0
lock_acquire+0x160/0x308
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
coresight_set_assoc_ectdev_mutex+0x3c/0x5c
cti_update_conn_xrefs+0x6c/0xf8
cti_probe+0x33c/0x394
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(ect_mutex);
lock(coresight_mutex);
lock(ect_mutex);
lock(coresight_mutex);
*** DEADLOCK ***
4 locks held by kworker/u12:1/53:
#0: ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1fc/0x63c
#1: (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x228/0x63c
#2: (&dev->mutex){....}-{4:4}, at: __device_attach+0x48/0x1a8
#3: (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
To fix the same, call cti_add_assoc_to_csdev without the holding
coresight_mutex and confine the locking while setting the associated
ect / cti device using coresight_set_assoc_ectdev_mutex().
Fixes: 177af8285b ("coresight: cti: Enable CTI associated with devices")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220721130329.3787211-1-sudeep.holla@arm.com
New csdev_access functions were added as part of the previous
refactor. In order to make them more consistent with the
existing ones, change any signed offset types to be unsigned.
Now that they are unsigned, stop using hi_off = -1 to signify
a single 32bit access. Instead just call the existing 32bit
accessors. This is also applied to other parts of the codebase,
and the coresight_{read,write}_reg_pair() functions can be
deleted.
Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20220830172614.340962-6-james.clark@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
coresight devices track their connections (output connections) and
hold a reference to the fwnode. When a device goes away, we walk through
the devices on the coresight bus and make sure that the references
are dropped. This happens both ways:
a) For all output connections from the device, drop the reference to
the target device via coresight_release_platform_data()
b) Iterate over all the devices on the coresight bus and drop the
reference to fwnode if *this* device is the target of the output
connection, via coresight_remove_conns()->coresight_remove_match().
However, the coresight_remove_match() doesn't clear the fwnode field,
after dropping the reference, this causes use-after-free and
additional refcount drops on the fwnode.
e.g., if we have two devices, A and B, with a connection, A -> B.
If we remove B first, B would clear the reference on B, from A
via coresight_remove_match(). But when A is removed, it still has
a connection with fwnode still pointing to B. Thus it tries to drops
the reference in coresight_release_platform_data(), raising the bells
like :
[ 91.990153] ------------[ cut here ]------------
[ 91.990163] refcount_t: addition on 0; use-after-free.
[ 91.990212] WARNING: CPU: 0 PID: 461 at lib/refcount.c:25 refcount_warn_saturate+0xa0/0x144
[ 91.990260] Modules linked in: coresight_funnel coresight_replicator coresight_etm4x(-)
crct10dif_ce coresight ip_tables x_tables ipv6 [last unloaded: coresight_cpu_debug]
[ 91.990398] CPU: 0 PID: 461 Comm: rmmod Tainted: G W T 5.19.0-rc2+ #53
[ 91.990418] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb 1 2019
[ 91.990434] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 91.990454] pc : refcount_warn_saturate+0xa0/0x144
[ 91.990476] lr : refcount_warn_saturate+0xa0/0x144
[ 91.990496] sp : ffff80000c843640
[ 91.990509] x29: ffff80000c843640 x28: ffff800009957c28 x27: ffff80000c8439a8
[ 91.990560] x26: ffff00097eff1990 x25: ffff8000092b6ad8 x24: ffff00097eff19a8
[ 91.990610] x23: ffff80000c8439a8 x22: 0000000000000000 x21: ffff80000c8439c2
[ 91.990659] x20: 0000000000000000 x19: ffff00097eff1a10 x18: ffff80000ab99c40
[ 91.990708] x17: 0000000000000000 x16: 0000000000000000 x15: ffff80000abf6fa0
[ 91.990756] x14: 000000000000001d x13: 0a2e656572662d72 x12: 657466612d657375
[ 91.990805] x11: 203b30206e6f206e x10: 6f69746964646120 x9 : ffff8000081aba28
[ 91.990854] x8 : 206e6f206e6f6974 x7 : 69646461203a745f x6 : 746e756f63666572
[ 91.990903] x5 : ffff00097648ec58 x4 : 0000000000000000 x3 : 0000000000000027
[ 91.990952] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff00080260ba00
[ 91.991000] Call trace:
[ 91.991012] refcount_warn_saturate+0xa0/0x144
[ 91.991034] kobject_get+0xac/0xb0
[ 91.991055] of_node_get+0x2c/0x40
[ 91.991076] of_fwnode_get+0x40/0x60
[ 91.991094] fwnode_handle_get+0x3c/0x60
[ 91.991116] fwnode_get_nth_parent+0xf4/0x110
[ 91.991137] fwnode_full_name_string+0x48/0xc0
[ 91.991158] device_node_string+0x41c/0x530
[ 91.991178] pointer+0x320/0x3ec
[ 91.991198] vsnprintf+0x23c/0x750
[ 91.991217] vprintk_store+0x104/0x4b0
[ 91.991238] vprintk_emit+0x8c/0x360
[ 91.991257] vprintk_default+0x44/0x50
[ 91.991276] vprintk+0xcc/0xf0
[ 91.991295] _printk+0x68/0x90
[ 91.991315] of_node_release+0x13c/0x14c
[ 91.991334] kobject_put+0x98/0x114
[ 91.991354] of_node_put+0x24/0x34
[ 91.991372] of_fwnode_put+0x40/0x5c
[ 91.991390] fwnode_handle_put+0x38/0x50
[ 91.991411] coresight_release_platform_data+0x74/0xb0 [coresight]
[ 91.991472] coresight_unregister+0x64/0xcc [coresight]
[ 91.991525] etm4_remove_dev+0x64/0x78 [coresight_etm4x]
[ 91.991563] etm4_remove_amba+0x1c/0x2c [coresight_etm4x]
[ 91.991598] amba_remove+0x3c/0x19c
Reproducible by: (Build all coresight components as modules):
#!/bin/sh
while true
do
for m in tmc stm cpu_debug etm4x replicator funnel
do
modprobe coresight_${m}
done
for m in tmc stm cpu_debug etm4x replicator funnel
do
rmmode coresight_${m}
done
done
Cc: stable@vger.kernel.org
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Fixes: 37ea1ffddf ("coresight: Use fwnode handle instead of device names")
Link: https://lore.kernel.org/r/20220614214024.3005275-1-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
It is possibe that probe failure issue happens when the device
and its child_device's probe happens at the same time.
In coresight_make_links, has_conns_grp is true for parent, but
has_conns_grp is false for child device as has_conns_grp is set
to true in coresight_create_conns_sysfs_group. The probe of parent
device will fail at this condition. Add has_conns_grp check for
child device before make the links and make the process from
device_register to connection_create be atomic to avoid this
probe failure issue.
Cc: stable@vger.kernel.org
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Suggested-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
Link: https://lore.kernel.org/r/20220309142206.15632-1-quic_jinlmao@quicinc.com
[ Added Cc stable ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
