linux-toradex.git/drivers/opp/core.c, branch v5.14

opp: core: Check for pending links before reading required_opp pointers

2021-08-23T07:14:55+00:00

Commit 4fa82a87ba55 ("opp: Allow required-opps to be used for non genpd
use cases") dereferences the pointers in required_opp_tables but these
might be set to an ERR_PTR if the list still has lazy links pending,
resulting in segfaults.  Prior to this patch IS_ERR was also checked on
required_opp_tables[i] before reading ->is_genpd inside
_opp_table_alloc_required_tables, which is at the same time the
predicate to add this table to the lazy list.  This segfault is solved
by reordering the checks to bail on lazy pending tables before reading
->is_genpd.

Fixes: 4fa82a87ba55 ("opp: Allow required-opps to be used for non genpd use cases")
Reviewed-by: AngeloGioacchino Del Regno 
Signed-off-by: Marijn Suijten 
Signed-off-by: Viresh Kumar

opp: Drop empty-table checks from _put functions

2021-08-16T04:12:08+00:00

The current_opp is released only when whole OPP table is released,
otherwise it's only marked as removed by dev_pm_opp_remove_table().
Functions like dev_pm_opp_put_clkname() and dev_pm_opp_put_supported_hw()
are checking whether OPP table is empty and it's not if current_opp is
set since it holds the refcount of OPP, this produces a noisy warning
from these functions about busy OPP table. Remove the checks to fix it.

Cc: stable@vger.kernel.org
Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Allow required-opps to be used for non genpd use cases

2021-06-18T03:30:55+00:00

Don't limit required_opp_table to genpd only. One possible use case is
cpufreq based devfreq governor, which can use required-opps property to
derive devfreq from cpufreq.

Though the OPP core still doesn't support non-genpd required-opps in
_set_required_opps().

Suggested-by: Chanwoo Choi 
Signed-off-by: Hsin-Yi Wang 
[ Viresh: Update _set_required_opps() to check for genpd ]
Signed-off-by: Viresh Kumar

opp: Change return type of devm_pm_opp_attach_genpd()

2021-03-16T04:44:11+00:00

Make devm_pm_opp_attach_genpd() to return error code instead of
opp_table pointer in order to have return type consistent with the
other resource-managed OPP helpers.

Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Change return type of devm_pm_opp_register_set_opp_helper()

2021-03-16T04:44:11+00:00

Make devm_pm_opp_register_set_opp_helper() to return error code instead
of opp_table pointer in order to have return type consistent with the
other resource-managed OPP helpers.

Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Add devres wrapper for dev_pm_opp_set_supported_hw

2021-03-15T03:56:53+00:00

Add devres wrapper for dev_pm_opp_set_supported_hw() to simplify drivers
code.

Signed-off-by: Yangtao Li 
Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Add devres wrapper for dev_pm_opp_set_regulators

2021-03-15T03:56:53+00:00

Add devres wrapper for dev_pm_opp_set_regulators() to simplify drivers
code.

Signed-off-by: Yangtao Li 
Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Add devres wrapper for dev_pm_opp_set_clkname

2021-03-15T03:56:53+00:00

Add devres wrapper for dev_pm_opp_set_clkname() to simplify drivers code.

Signed-off-by: Yangtao Li 
Signed-off-by: Dmitry Osipenko 
Signed-off-by: Viresh Kumar

opp: Don't drop extra references to OPPs accidentally

2021-03-12T03:56:52+00:00

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

opp: Don't skip freq update for different frequency

2021-02-18T07:01:08+00:00

We skip the OPP update if the current and target OPPs are same. This is
fine for the devices that don't support frequency but may cause issues
for the ones that need to program frequency.

An OPP entry doesn't really signify a single operating frequency but
rather the highest frequency at which the other properties of the OPP
entry apply. And we may reach here with different frequency values,
while all of them would point to the same OPP entry in the OPP table.

We just need to update the clock frequency in that case, though in order
to not add special exit points we reuse the code flow from a normal
path.

While at it, rearrange the conditionals in the 'if' statement to check
'enabled' flag at the end.

Fixes: 81c4d8a3c414 ("opp: Keep track of currently programmed OPP")
Signed-off-by: Jonathan Marek 
[ Viresh: Improved commit log and subject, rename current_freq as
	  current_rate, document it, remove local variable and rearrange
	  code. ]
Signed-off-by: Viresh Kumar