| Message ID | 20200727093047.8274-1-stephan@gerhold.net (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | [RFC,1/2] opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER | expand |
On Mon, 27 Jul 2020 at 11:31, Stephan Gerhold <stephan@gerhold.net> wrote: > > The OPP core manages various resources, e.g. clocks or interconnect paths. > These resources are looked up when the OPP table is allocated once > dev_pm_opp_get_opp_table() is called the first time (either directly > or indirectly through one of the many helper functions). > > At this point, the resources may not be available yet, i.e. looking them > up will result in -EPROBE_DEFER. Unfortunately, dev_pm_opp_get_opp_table() > is currently unable to propagate this error code since it only returns > the allocated OPP table or NULL. > > This means that all consumers of the OPP core are required to make sure > that all necessary resources are available. Usually this happens by > requesting them, checking the result and releasing them immediately after. > > For example, we have added "dev_pm_opp_of_find_icc_paths(dev, NULL)" to > several drivers now just to make sure the interconnect providers are > ready before the OPP table is allocated. If this call is missing, > the OPP core will only warn about this and then attempt to continue > without interconnect. This will eventually fail horribly, e.g.: > > cpu cpu0: _allocate_opp_table: Error finding interconnect paths: -517 > ... later ... > of: _read_bw: Mismatch between opp-peak-kBps and paths (1 0) > cpu cpu0: _opp_add_static_v2: opp key field not found > cpu cpu0: _of_add_opp_table_v2: Failed to add OPP, -22 > > This example happens when trying to use interconnects for a CPU OPP > table together with qcom-cpufreq-nvmem.c. qcom-cpufreq-nvmem calls > dev_pm_opp_set_supported_hw(), which ends up allocating the OPP table > early. To fix the problem with the current approach we would need to add > yet another call to dev_pm_opp_of_find_icc_paths(dev, NULL). > But actually qcom-cpufreq-nvmem.c has nothing to do with interconnects... > > This commit attempts to make this more robust by allowing > dev_pm_opp_get_opp_table() to return an error pointer. Fixing all > the usages is trivial because the function is usually used indirectly > through another helper (e.g. dev_pm_opp_set_supported_hw() above). > These other helpers already return an error pointer. > > The example above then works correctly because set_supported_hw() will > return -EPROBE_DEFER, and qcom-cpufreq-nvmem.c already propagates that > error. It should also be possible to remove the remaining usages of > "dev_pm_opp_of_find_icc_paths(dev, NULL)" from other drivers as well. > > Note that this commit currently only handles -EPROBE_DEFER for the > clock/interconnects within _allocate_opp_table(). Other errors are just > ignored as before. Eventually those should be propagated as well. > > Signed-off-by: Stephan Gerhold <stephan@gerhold.net> > --- > I wasn't sure if the changes in drivers/base/power/domain.c > should be made in a separate commit, but they need to be made together > with the other changes. I would suggest to move the changes in drivers/base/power/domain.c into a separate patch, still part of the series, but let it preceed $subject patch. > > Also note that this is RFC because this is just something I got really > frustrated about. There might be situations where this won't work correctly...? > --- > drivers/base/power/domain.c | 28 ++++++++++++++++++----- The above changes look good to me. For the below, at a quick look I have no objections, but I am deferring to Viresh to have a closer look. Kind regards Uffe > drivers/opp/core.c | 45 ++++++++++++++++++++++--------------- > drivers/opp/of.c | 8 +++---- > 3 files changed, 53 insertions(+), 28 deletions(-) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 2cb5e04cf86c..c50f2de952c4 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -2044,8 +2044,9 @@ int of_genpd_add_provider_simple(struct device_node *np, > if (genpd->set_performance_state) { > ret = dev_pm_opp_of_add_table(&genpd->dev); > if (ret) { > - dev_err(&genpd->dev, "Failed to add OPP table: %d\n", > - ret); > + if (ret != -EPROBE_DEFER) > + dev_err(&genpd->dev, "Failed to add OPP table: %d\n", > + ret); > goto unlock; > } > > @@ -2054,7 +2055,14 @@ int of_genpd_add_provider_simple(struct device_node *np, > * state. > */ > genpd->opp_table = dev_pm_opp_get_opp_table(&genpd->dev); > - WARN_ON(!genpd->opp_table); > + if (IS_ERR(genpd->opp_table)) { > + if (PTR_ERR(genpd->opp_table) != -EPROBE_DEFER) > + dev_err(&genpd->dev, "Failed to get OPP table: %pe\n", > + genpd->opp_table); > + > + dev_pm_opp_of_remove_table(&genpd->dev); > + goto unlock; > + } > } > > ret = genpd_add_provider(np, genpd_xlate_simple, genpd); > @@ -2111,8 +2119,9 @@ int of_genpd_add_provider_onecell(struct device_node *np, > if (genpd->set_performance_state) { > ret = dev_pm_opp_of_add_table_indexed(&genpd->dev, i); > if (ret) { > - dev_err(&genpd->dev, "Failed to add OPP table for index %d: %d\n", > - i, ret); > + if (ret != -EPROBE_DEFER) > + dev_err(&genpd->dev, "Failed to add OPP table for index %d: %d\n", > + i, ret); > goto error; > } > > @@ -2121,7 +2130,14 @@ int of_genpd_add_provider_onecell(struct device_node *np, > * performance state. > */ > genpd->opp_table = dev_pm_opp_get_opp_table_indexed(&genpd->dev, i); > - WARN_ON(!genpd->opp_table); > + if (IS_ERR(genpd->opp_table)) { > + if (PTR_ERR(genpd->opp_table) != -EPROBE_DEFER) > + dev_err(&genpd->dev, "Failed to get OPP table: %pe\n", > + genpd->opp_table); > + > + dev_pm_opp_of_remove_table(&genpd->dev); > + goto error; > + } > } > > genpd->provider = &np->fwnode; > diff --git a/drivers/opp/core.c b/drivers/opp/core.c > index 9d7fb45b1786..45d24de75e0e 100644 > --- a/drivers/opp/core.c > +++ b/drivers/opp/core.c > @@ -1063,7 +1063,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) > */ > opp_table = kzalloc(sizeof(*opp_table), GFP_KERNEL); > if (!opp_table) > - return NULL; > + return ERR_PTR(-ENOMEM); > > mutex_init(&opp_table->lock); > mutex_init(&opp_table->genpd_virt_dev_lock); > @@ -1074,8 +1074,8 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) > > opp_dev = _add_opp_dev(dev, opp_table); > if (!opp_dev) { > - kfree(opp_table); > - return NULL; > + ret = -ENOMEM; > + goto err; > } > > _of_init_opp_table(opp_table, dev, index); > @@ -1087,13 +1087,18 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) > if (ret != -EPROBE_DEFER) > dev_dbg(dev, "%s: Couldn't find clock: %d\n", __func__, > ret); > + else > + goto err; > } > > /* Find interconnect path(s) for the device */ > ret = dev_pm_opp_of_find_icc_paths(dev, opp_table); > - if (ret) > + if (ret) { > + if (ret == -EPROBE_DEFER) > + goto err; > dev_warn(dev, "%s: Error finding interconnect paths: %d\n", > __func__, ret); > + } > > BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head); > INIT_LIST_HEAD(&opp_table->opp_list); > @@ -1102,6 +1107,10 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) > /* Secure the device table modification */ > list_add(&opp_table->node, &opp_tables); > return opp_table; > + > +err: > + kfree(opp_table); > + return ERR_PTR(ret); > } > > void _get_opp_table_kref(struct opp_table *opp_table) > @@ -1568,8 +1577,8 @@ struct opp_table *dev_pm_opp_set_supported_hw(struct device *dev, > struct opp_table *opp_table; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (IS_ERR(opp_table)) > + return opp_table; > > /* Make sure there are no concurrent readers while updating opp_table */ > WARN_ON(!list_empty(&opp_table->opp_list)); > @@ -1627,8 +1636,8 @@ struct opp_table *dev_pm_opp_set_prop_name(struct device *dev, const char *name) > struct opp_table *opp_table; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (IS_ERR(opp_table)) > + return opp_table; > > /* Make sure there are no concurrent readers while updating opp_table */ > WARN_ON(!list_empty(&opp_table->opp_list)); > @@ -1720,8 +1729,8 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev, > int ret, i; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (IS_ERR(opp_table)) > + return opp_table; > > /* This should be called before OPPs are initialized */ > if (WARN_ON(!list_empty(&opp_table->opp_list))) { > @@ -1830,8 +1839,8 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name) > int ret; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (IS_ERR(opp_table)) > + return opp_table; > > /* This should be called before OPPs are initialized */ > if (WARN_ON(!list_empty(&opp_table->opp_list))) { > @@ -1898,8 +1907,8 @@ struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, > return ERR_PTR(-EINVAL); > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (!IS_ERR(opp_table)) > + return opp_table; > > /* This should be called before OPPs are initialized */ > if (WARN_ON(!list_empty(&opp_table->opp_list))) { > @@ -1979,8 +1988,8 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, > const char **name = names; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return ERR_PTR(-ENOMEM); > + if (IS_ERR(opp_table)) > + return opp_table; > > /* > * If the genpd's OPP table isn't already initialized, parsing of the > @@ -2150,8 +2159,8 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) > int ret; > > opp_table = dev_pm_opp_get_opp_table(dev); > - if (!opp_table) > - return -ENOMEM; > + if (IS_ERR(opp_table)) > + return PTR_ERR(opp_table); > > /* Fix regulator count for dynamic OPPs */ > opp_table->regulator_count = 1; > diff --git a/drivers/opp/of.c b/drivers/opp/of.c > index 0430290670ab..d8b623cc015a 100644 > --- a/drivers/opp/of.c > +++ b/drivers/opp/of.c > @@ -947,8 +947,8 @@ int dev_pm_opp_of_add_table(struct device *dev) > int ret; > > opp_table = dev_pm_opp_get_opp_table_indexed(dev, 0); > - if (!opp_table) > - return -ENOMEM; > + if (IS_ERR(opp_table)) > + return PTR_ERR(opp_table); > > /* > * OPPs have two version of bindings now. Also try the old (v1) > @@ -1002,8 +1002,8 @@ int dev_pm_opp_of_add_table_indexed(struct device *dev, int index) > } > > opp_table = dev_pm_opp_get_opp_table_indexed(dev, index); > - if (!opp_table) > - return -ENOMEM; > + if (IS_ERR(opp_table)) > + return PTR_ERR(opp_table); > > ret = _of_add_opp_table_v2(dev, opp_table); > if (ret) > -- > 2.27.0 >
On Wed, Aug 12, 2020 at 11:10:38AM +0200, Ulf Hansson wrote: > > I wasn't sure if the changes in drivers/base/power/domain.c > > should be made in a separate commit, but they need to be made together > > with the other changes. > > I would suggest to move the changes in drivers/base/power/domain.c > into a separate patch, still part of the series, but let it preceed > $subject patch. > OK, will do that in v2 - thank you! I have another small build fix reported by the kernel test robot, but will wait with sending that out until Viresh had a chance to give some feedback on the basic idea. :) Thanks! Stephan
On 12-08-20, 12:53, Stephan Gerhold wrote: > On Wed, Aug 12, 2020 at 11:10:38AM +0200, Ulf Hansson wrote: > > > I wasn't sure if the changes in drivers/base/power/domain.c > > > should be made in a separate commit, but they need to be made together > > > with the other changes. > > > > I would suggest to move the changes in drivers/base/power/domain.c > > into a separate patch, still part of the series, but let it preceed > > $subject patch. > > > > OK, will do that in v2 - thank you! > > I have another small build fix reported by the kernel test robot, > but will wait with sending that out until Viresh had a chance to give > some feedback on the basic idea. :) What was the issue that was reported ? I may end up applying V1 only with some of my changes.
Hi Viresh, On Wed, Aug 12, 2020 at 08:31:22PM +0530, Viresh Kumar wrote: > On 12-08-20, 12:53, Stephan Gerhold wrote: > > I have another small build fix reported by the kernel test robot, > > but will wait with sending that out until Viresh had a chance to give > > some feedback on the basic idea. :) > > What was the issue that was reported ? I may end up applying V1 only > with some of my changes. > It was this build error on SH (for the second patch): >> drivers/cpufreq/cpufreq-dt.c:36:29: error: conflicting types for 'cpu_data' 36 | static struct private_data *cpu_data; | ^~~~~~~~ In file included from arch/sh/include/asm/thread_info.h:27, from include/linux/thread_info.h:38, from include/asm-generic/current.h:5, from ./arch/sh/include/generated/asm/current.h:1, from include/linux/mutex.h:14, from include/linux/notifier.h:14, from include/linux/clk.h:14, from drivers/cpufreq/cpufreq-dt.c:11: arch/sh/include/asm/processor.h:90:26: note: previous declaration of 'cpu_data' was here 90 | extern struct sh_cpuinfo cpu_data[]; | ^~~~~~~~ I fixed it by renaming "cpu_data" to "cpufreq_dt_data". (I could not think of a better name so feel free to use something else...) Thanks! Stephan
On 12-08-20, 11:10, Ulf Hansson wrote: > On Mon, 27 Jul 2020 at 11:31, Stephan Gerhold <stephan@gerhold.net> wrote: > > I wasn't sure if the changes in drivers/base/power/domain.c > > should be made in a separate commit, but they need to be made together > > with the other changes. > > I would suggest to move the changes in drivers/base/power/domain.c > into a separate patch, still part of the series, but let it preceed > $subject patch. That can't be done as the return type of a routine was changing and that needs to be sorted out in the same patch.
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 2cb5e04cf86c..c50f2de952c4 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -2044,8 +2044,9 @@ int of_genpd_add_provider_simple(struct device_node *np, if (genpd->set_performance_state) { ret = dev_pm_opp_of_add_table(&genpd->dev); if (ret) { - dev_err(&genpd->dev, "Failed to add OPP table: %d\n", - ret); + if (ret != -EPROBE_DEFER) + dev_err(&genpd->dev, "Failed to add OPP table: %d\n", + ret); goto unlock; } @@ -2054,7 +2055,14 @@ int of_genpd_add_provider_simple(struct device_node *np, * state. */ genpd->opp_table = dev_pm_opp_get_opp_table(&genpd->dev); - WARN_ON(!genpd->opp_table); + if (IS_ERR(genpd->opp_table)) { + if (PTR_ERR(genpd->opp_table) != -EPROBE_DEFER) + dev_err(&genpd->dev, "Failed to get OPP table: %pe\n", + genpd->opp_table); + + dev_pm_opp_of_remove_table(&genpd->dev); + goto unlock; + } } ret = genpd_add_provider(np, genpd_xlate_simple, genpd); @@ -2111,8 +2119,9 @@ int of_genpd_add_provider_onecell(struct device_node *np, if (genpd->set_performance_state) { ret = dev_pm_opp_of_add_table_indexed(&genpd->dev, i); if (ret) { - dev_err(&genpd->dev, "Failed to add OPP table for index %d: %d\n", - i, ret); + if (ret != -EPROBE_DEFER) + dev_err(&genpd->dev, "Failed to add OPP table for index %d: %d\n", + i, ret); goto error; } @@ -2121,7 +2130,14 @@ int of_genpd_add_provider_onecell(struct device_node *np, * performance state. */ genpd->opp_table = dev_pm_opp_get_opp_table_indexed(&genpd->dev, i); - WARN_ON(!genpd->opp_table); + if (IS_ERR(genpd->opp_table)) { + if (PTR_ERR(genpd->opp_table) != -EPROBE_DEFER) + dev_err(&genpd->dev, "Failed to get OPP table: %pe\n", + genpd->opp_table); + + dev_pm_opp_of_remove_table(&genpd->dev); + goto error; + } } genpd->provider = &np->fwnode; diff --git a/drivers/opp/core.c b/drivers/opp/core.c index 9d7fb45b1786..45d24de75e0e 100644 --- a/drivers/opp/core.c +++ b/drivers/opp/core.c @@ -1063,7 +1063,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) */ opp_table = kzalloc(sizeof(*opp_table), GFP_KERNEL); if (!opp_table) - return NULL; + return ERR_PTR(-ENOMEM); mutex_init(&opp_table->lock); mutex_init(&opp_table->genpd_virt_dev_lock); @@ -1074,8 +1074,8 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) opp_dev = _add_opp_dev(dev, opp_table); if (!opp_dev) { - kfree(opp_table); - return NULL; + ret = -ENOMEM; + goto err; } _of_init_opp_table(opp_table, dev, index); @@ -1087,13 +1087,18 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) if (ret != -EPROBE_DEFER) dev_dbg(dev, "%s: Couldn't find clock: %d\n", __func__, ret); + else + goto err; } /* Find interconnect path(s) for the device */ ret = dev_pm_opp_of_find_icc_paths(dev, opp_table); - if (ret) + if (ret) { + if (ret == -EPROBE_DEFER) + goto err; dev_warn(dev, "%s: Error finding interconnect paths: %d\n", __func__, ret); + } BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head); INIT_LIST_HEAD(&opp_table->opp_list); @@ -1102,6 +1107,10 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index) /* Secure the device table modification */ list_add(&opp_table->node, &opp_tables); return opp_table; + +err: + kfree(opp_table); + return ERR_PTR(ret); } void _get_opp_table_kref(struct opp_table *opp_table) @@ -1568,8 +1577,8 @@ struct opp_table *dev_pm_opp_set_supported_hw(struct device *dev, struct opp_table *opp_table; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (IS_ERR(opp_table)) + return opp_table; /* Make sure there are no concurrent readers while updating opp_table */ WARN_ON(!list_empty(&opp_table->opp_list)); @@ -1627,8 +1636,8 @@ struct opp_table *dev_pm_opp_set_prop_name(struct device *dev, const char *name) struct opp_table *opp_table; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (IS_ERR(opp_table)) + return opp_table; /* Make sure there are no concurrent readers while updating opp_table */ WARN_ON(!list_empty(&opp_table->opp_list)); @@ -1720,8 +1729,8 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev, int ret, i; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (IS_ERR(opp_table)) + return opp_table; /* This should be called before OPPs are initialized */ if (WARN_ON(!list_empty(&opp_table->opp_list))) { @@ -1830,8 +1839,8 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name) int ret; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (IS_ERR(opp_table)) + return opp_table; /* This should be called before OPPs are initialized */ if (WARN_ON(!list_empty(&opp_table->opp_list))) { @@ -1898,8 +1907,8 @@ struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, return ERR_PTR(-EINVAL); opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (!IS_ERR(opp_table)) + return opp_table; /* This should be called before OPPs are initialized */ if (WARN_ON(!list_empty(&opp_table->opp_list))) { @@ -1979,8 +1988,8 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **name = names; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return ERR_PTR(-ENOMEM); + if (IS_ERR(opp_table)) + return opp_table; /* * If the genpd's OPP table isn't already initialized, parsing of the @@ -2150,8 +2159,8 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) int ret; opp_table = dev_pm_opp_get_opp_table(dev); - if (!opp_table) - return -ENOMEM; + if (IS_ERR(opp_table)) + return PTR_ERR(opp_table); /* Fix regulator count for dynamic OPPs */ opp_table->regulator_count = 1; diff --git a/drivers/opp/of.c b/drivers/opp/of.c index 0430290670ab..d8b623cc015a 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c @@ -947,8 +947,8 @@ int dev_pm_opp_of_add_table(struct device *dev) int ret; opp_table = dev_pm_opp_get_opp_table_indexed(dev, 0); - if (!opp_table) - return -ENOMEM; + if (IS_ERR(opp_table)) + return PTR_ERR(opp_table); /* * OPPs have two version of bindings now. Also try the old (v1) @@ -1002,8 +1002,8 @@ int dev_pm_opp_of_add_table_indexed(struct device *dev, int index) } opp_table = dev_pm_opp_get_opp_table_indexed(dev, index); - if (!opp_table) - return -ENOMEM; + if (IS_ERR(opp_table)) + return PTR_ERR(opp_table); ret = _of_add_opp_table_v2(dev, opp_table); if (ret)
The OPP core manages various resources, e.g. clocks or interconnect paths. These resources are looked up when the OPP table is allocated once dev_pm_opp_get_opp_table() is called the first time (either directly or indirectly through one of the many helper functions). At this point, the resources may not be available yet, i.e. looking them up will result in -EPROBE_DEFER. Unfortunately, dev_pm_opp_get_opp_table() is currently unable to propagate this error code since it only returns the allocated OPP table or NULL. This means that all consumers of the OPP core are required to make sure that all necessary resources are available. Usually this happens by requesting them, checking the result and releasing them immediately after. For example, we have added "dev_pm_opp_of_find_icc_paths(dev, NULL)" to several drivers now just to make sure the interconnect providers are ready before the OPP table is allocated. If this call is missing, the OPP core will only warn about this and then attempt to continue without interconnect. This will eventually fail horribly, e.g.: cpu cpu0: _allocate_opp_table: Error finding interconnect paths: -517 ... later ... of: _read_bw: Mismatch between opp-peak-kBps and paths (1 0) cpu cpu0: _opp_add_static_v2: opp key field not found cpu cpu0: _of_add_opp_table_v2: Failed to add OPP, -22 This example happens when trying to use interconnects for a CPU OPP table together with qcom-cpufreq-nvmem.c. qcom-cpufreq-nvmem calls dev_pm_opp_set_supported_hw(), which ends up allocating the OPP table early. To fix the problem with the current approach we would need to add yet another call to dev_pm_opp_of_find_icc_paths(dev, NULL). But actually qcom-cpufreq-nvmem.c has nothing to do with interconnects... This commit attempts to make this more robust by allowing dev_pm_opp_get_opp_table() to return an error pointer. Fixing all the usages is trivial because the function is usually used indirectly through another helper (e.g. dev_pm_opp_set_supported_hw() above). These other helpers already return an error pointer. The example above then works correctly because set_supported_hw() will return -EPROBE_DEFER, and qcom-cpufreq-nvmem.c already propagates that error. It should also be possible to remove the remaining usages of "dev_pm_opp_of_find_icc_paths(dev, NULL)" from other drivers as well. Note that this commit currently only handles -EPROBE_DEFER for the clock/interconnects within _allocate_opp_table(). Other errors are just ignored as before. Eventually those should be propagated as well. Signed-off-by: Stephan Gerhold <stephan@gerhold.net> --- I wasn't sure if the changes in drivers/base/power/domain.c should be made in a separate commit, but they need to be made together with the other changes. Also note that this is RFC because this is just something I got really frustrated about. There might be situations where this won't work correctly...? --- drivers/base/power/domain.c | 28 ++++++++++++++++++----- drivers/opp/core.c | 45 ++++++++++++++++++++++--------------- drivers/opp/of.c | 8 +++---- 3 files changed, 53 insertions(+), 28 deletions(-)