linux-stable.git/drivers/opp/opp.h, branch linux-5.11.y

opp: Don't drop extra references to OPPs accidentally

2021-03-17T16:11:35+00:00

commit 606a5d4227e4610399c61086ac55c46068a90b03 upstream.

We are required to call dev_pm_opp_put() from outside of the
opp_table->lock as debugfs removal needs to happen lock-less to avoid
circular dependency issues.

commit cf1fac943c63 ("opp: Reduce the size of critical section in
_opp_kref_release()") tried to fix that introducing a new routine
_opp_get_next() which keeps returning OPPs that can be freed by the
callers and this routine shall be called without holding the
opp_table->lock.

Though the commit overlooked the fact that the OPPs can be referenced by
other users as well and this routine will end up dropping references
which were taken by other users and hence freeing the OPPs prematurely.

In effect, other users of the OPPs will end up having invalid pointers
at hand. We didn't see any crash reports earlier as the exact situation
never happened, though it is certainly possible.

We need a way to mark which OPPs are no longer referenced by the OPP
core, so we don't drop extra references to them accidentally.

This commit adds another OPP flag, "removed", which is used to track
this. And now we should never end up dropping extra references to the
OPPs.

Cc: v5.11+  # v5.11+
Fixes: cf1fac943c63 ("opp: Reduce the size of critical section in _opp_kref_release()")
Signed-off-by: Beata Michalska 
[ Viresh: Almost rewrote entire patch, added new "removed" field,
	  rewrote commit log and added the correct Fixes tag. ]
Co-developed-by: Viresh Kumar 
Signed-off-by: Viresh Kumar 
Signed-off-by: Greg Kroah-Hartman

opp: Don't create an OPP table from dev_pm_opp_get_opp_table()

2020-12-09T05:51:11+00:00

It has been found that some users (like cpufreq-dt and others on LKML)
have abused the helper dev_pm_opp_get_opp_table() to create the OPP
table instead of just finding it, which is the wrong thing to do. This
routine was meant for OPP core's internal working and exposed the whole
functionality by mistake.

Change the scope of dev_pm_opp_get_opp_table() to only finding the
table. The internal helpers _opp_get_opp_table*() are thus renamed to
_add_opp_table*(), dev_pm_opp_get_opp_table_indexed() is removed (as we
don't need the index field for finding the OPP table) and so the only
user, genpd, is updated.

Note that the prototype of _add_opp_table() was already left in opp.h by
mistake when it was removed earlier and so we weren't required to add it
now.

Acked-by: Ulf Hansson 
Signed-off-by: Viresh Kumar

Merge branch 'opp/linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm

2020-10-05T11:31:32+00:00

Pull opertaing performance points (OPP) framework fixes for 5.10-rc1
from Viresh Kumar:

"- Return -EPROBE_DEFER properly from dev_pm_opp_get_opp_table()
   (Stephan Gerhold).

 - Minor cleanups around required-opps (Stephan Gerhold).

 - Extends opp-supported-hw property to contain multiple versions
   (Viresh Kumar).

 - Multiple cleanups around dev_pm_opp_attach_genpd() (Viresh Kumar).

 - Multiple fixes, cleanups in the OPP core for overall better design
   (Viresh Kumar)."

* 'opp/linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm:
  opp: Allow opp-level to be set to 0
  opp: Prevent memory leak in dev_pm_opp_attach_genpd()
  ARM: tegra: Pass multiple versions in opp-supported-hw property
  opp: Allow opp-supported-hw to contain multiple versions
  dt-bindings: opp: Allow opp-supported-hw to contain multiple versions
  opp: Set required OPPs in reverse order when scaling down
  opp: Reduce code duplication in _set_required_opps()
  opp: Drop unnecessary check from dev_pm_opp_attach_genpd()
  opp: Handle multiple calls for same OPP table in _of_add_opp_table_v1()
  opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER
  opp: Remove _dev_pm_opp_find_and_remove_table() wrapper
  opp: Split out _opp_set_rate_zero()
  opp: Reuse the enabled flag in !target_freq path
  opp: Rename regulator_enabled and use it as status of all resources

opp: Don't drop reference for an OPP table that was never parsed

2020-08-31T09:19:47+00:00

dev_pm_opp_remove_table() should drop a reference to the OPP table only
if the DT OPP table was parsed earlier with a call to
dev_pm_opp_of_add_table() earlier. Else it may end up dropping the
reference to the OPP table, which was added as a result of other calls
like dev_pm_opp_set_clkname(). And would hence result in undesirable
behavior later on when caller would try to free the resource again.

Fixes: 03758d60265c ("opp: Replace list_kref with a local counter")
Reported-by: Naresh Kamboju 
Reported-by: Anders Roxell 
Tested-by: Naresh Kamboju 
Signed-off-by: Viresh Kumar

opp: Remove _dev_pm_opp_find_and_remove_table() wrapper

2020-08-24T11:34:37+00:00

Remove the unnecessary wrapper and merge
_dev_pm_opp_find_and_remove_table() with dev_pm_opp_remove_table().

Tested-by: Rajendra Nayak 
Signed-off-by: Viresh Kumar

opp: Rename regulator_enabled and use it as status of all resources

2020-08-24T11:34:17+00:00

Expand the scope of the regulator_enabled flag and use it to track
status of all the resources. This will be used for other stuff in the
next patch.

Tested-by: Rajendra Nayak 
Signed-off-by: Viresh Kumar

opp: core: add regulators enable and disable

2020-05-29T04:45:12+00:00

Add enable regulators to dev_pm_opp_set_regulators() and disable
regulators to dev_pm_opp_put_regulators(). Even if bootloader
leaves regulators enabled, they should be enabled in kernel in
order to increase the reference count.

Tested-by: Marek Szyprowski 
Acked-by: Clément Péron 
Tested-by: Clément Péron 
Signed-off-by: Kamil Konieczny 
[ Viresh: Enable the regulator only after it is programmed and add a
	  flag to track its status. ]
Signed-off-by: Viresh Kumar

opp: Add support for parsing interconnect bandwidth

2020-05-29T04:45:08+00:00

The OPP bindings now support bandwidth values, so add support to parse it
from device tree and store it into the new dev_pm_opp_icc_bw struct, which
is part of the dev_pm_opp.

Signed-off-by: Georgi Djakov 
Reviewed-by: Matthias Kaehlcke 
[ Viresh: Create _read_bw() and use it, renamed _of_find_icc_paths() to
	  dev_pm_opp_of_find_icc_paths(), exported it and made opp_table
	  argument optional. Also drop the depends on from Kconfig. ]
Signed-off-by: Viresh Kumar

OPP: Add helpers for reading the binding properties

2020-05-13T06:18:13+00:00

The opp-hz DT property is not mandatory and we may use another property
as a key in the OPP table. Add helper functions to simplify the reading
and comparing the keys.

Signed-off-by: Saravana Kannan 
Signed-off-by: Georgi Djakov 
Reviewed-by: Matthias Kaehlcke 
Reviewed-by: Sibi Sankar 
[ Viresh: Removed an unnecessary comment ]
Signed-off-by: Viresh Kumar

opp: Replace list_kref with a local counter

2019-12-10T10:27:00+00:00

A kref or refcount isn't the right tool to be used here for counting
number of devices that are sharing the static OPPs created for the OPP
table. For example, we are reinitializing the kref again, after it
reaches a value of 0 and frees the resources, if the static OPPs get
added for the same OPP table structure (as the OPP table structure was
never freed). That is messy and very unclear.

This patch makes parsed_static_opps an unsigned integer and uses it to
count the number of users of the static OPPs. The increment and
decrement to parsed_static_opps is done under opp_table->lock now to
make sure no races are possible if the OPP table is getting added and
removed in parallel (which doesn't happen in practice, but can in
theory).

Signed-off-by: Viresh Kumar