From: Bjorn Andersson <bjorn.andersson@linaro.org> To: Rob Herring <robh@kernel.org>, Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linus Walleij <linus.walleij@linaro.org>, Alexander Graf <agraf@suse.de>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Kevin Hilman <khilman@kernel.org>, Ulf Hansson <ulf.hansson@linaro.org>, Joerg Roedel <joro@8bytes.org>, Robin Murphy <robin.murphy@arm.com>, Mark Brown <broonie@kernel.org>, Frank Rowand <frowand.list@gmail.com>, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, boot-architecture@lists.linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/8] driver core: make deferring probe after init optional Date: Thu, 24 May 2018 15:28:55 -0700 [thread overview] Message-ID: <20180524222855.GD14924@minitux> (raw) In-Reply-To: <20180524175024.19874-2-robh@kernel.org> On Thu 24 May 10:50 PDT 2018, Rob Herring wrote: > Deferred probe will currently wait forever on dependent devices to probe, > but sometimes a driver will never exist. It's also not always critical for > a driver to exist. Platforms can rely on default configuration from the > bootloader or reset defaults for things such as pinctrl and power domains. > This is often the case with initial platform support until various drivers > get enabled. There's at least 2 scenarios where deferred probe can render > a platform broken. Both involve using a DT which has more devices and > dependencies than the kernel supports. The 1st case is a driver may be > disabled in the kernel config. The 2nd case is the kernel version may > simply not have the dependent driver. This can happen if using a newer DT > (provided by firmware perhaps) with a stable kernel version. > > Subsystems or drivers may opt-in to this behavior by calling > driver_deferred_probe_check_init_done() instead of just returning > -EPROBE_DEFER. They may use additional information from DT or kernel's > config to decide whether to continue to defer probe or not. > For builtin drivers this still looks reasonable. But I would like to have an additional clarification here stating that drivers that might be targeted by this query must not be compiled as modules. And I would prefer to see an ack from e.g. Arnd that arm-soc is okay that we drop "tristate" on drivers affected by this; e.g. if we put this in the pinctrl core then all pinctrl drivers should be "bool" and so should any i2c, ssbi and spmi buses and drivers be. Regards, Bjorn > Cc: Alexander Graf <agraf@suse.de> > Signed-off-by: Rob Herring <robh@kernel.org> > --- > drivers/base/dd.c | 17 +++++++++++++++++ > include/linux/device.h | 2 ++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index c9f54089429b..d6034718da6f 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -226,6 +226,16 @@ void device_unblock_probing(void) > driver_deferred_probe_trigger(); > } > > +int driver_deferred_probe_check_init_done(struct device *dev, bool optional) > +{ > + if (optional && initcalls_done) { > + dev_WARN(dev, "ignoring dependency for device, assuming no driver"); > + return -ENODEV; > + } > + > + return -EPROBE_DEFER; > +} > + > /** > * deferred_probe_initcall() - Enable probing of deferred devices > * > @@ -240,6 +250,13 @@ static int deferred_probe_initcall(void) > /* Sort as many dependencies as possible before exiting initcalls */ > flush_work(&deferred_probe_work); > initcalls_done = true; > + > + /* > + * Trigger deferred probe again, this time we won't defer anything > + * that is optional > + */ > + driver_deferred_probe_trigger(); > + flush_work(&deferred_probe_work); > return 0; > } > late_initcall(deferred_probe_initcall); > diff --git a/include/linux/device.h b/include/linux/device.h > index 477956990f5e..f3dafd44c285 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -334,6 +334,8 @@ struct device *driver_find_device(struct device_driver *drv, > struct device *start, void *data, > int (*match)(struct device *dev, void *data)); > > +int driver_deferred_probe_check_init_done(struct device *dev, bool optional); > + > /** > * struct subsys_interface - interfaces to device functions > * @name: name of the device function > -- > 2.17.0 >
WARNING: multiple messages have this Message-ID (diff)
From: bjorn.andersson@linaro.org (Bjorn Andersson) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 1/8] driver core: make deferring probe after init optional Date: Thu, 24 May 2018 15:28:55 -0700 [thread overview] Message-ID: <20180524222855.GD14924@minitux> (raw) In-Reply-To: <20180524175024.19874-2-robh@kernel.org> On Thu 24 May 10:50 PDT 2018, Rob Herring wrote: > Deferred probe will currently wait forever on dependent devices to probe, > but sometimes a driver will never exist. It's also not always critical for > a driver to exist. Platforms can rely on default configuration from the > bootloader or reset defaults for things such as pinctrl and power domains. > This is often the case with initial platform support until various drivers > get enabled. There's at least 2 scenarios where deferred probe can render > a platform broken. Both involve using a DT which has more devices and > dependencies than the kernel supports. The 1st case is a driver may be > disabled in the kernel config. The 2nd case is the kernel version may > simply not have the dependent driver. This can happen if using a newer DT > (provided by firmware perhaps) with a stable kernel version. > > Subsystems or drivers may opt-in to this behavior by calling > driver_deferred_probe_check_init_done() instead of just returning > -EPROBE_DEFER. They may use additional information from DT or kernel's > config to decide whether to continue to defer probe or not. > For builtin drivers this still looks reasonable. But I would like to have an additional clarification here stating that drivers that might be targeted by this query must not be compiled as modules. And I would prefer to see an ack from e.g. Arnd that arm-soc is okay that we drop "tristate" on drivers affected by this; e.g. if we put this in the pinctrl core then all pinctrl drivers should be "bool" and so should any i2c, ssbi and spmi buses and drivers be. Regards, Bjorn > Cc: Alexander Graf <agraf@suse.de> > Signed-off-by: Rob Herring <robh@kernel.org> > --- > drivers/base/dd.c | 17 +++++++++++++++++ > include/linux/device.h | 2 ++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index c9f54089429b..d6034718da6f 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -226,6 +226,16 @@ void device_unblock_probing(void) > driver_deferred_probe_trigger(); > } > > +int driver_deferred_probe_check_init_done(struct device *dev, bool optional) > +{ > + if (optional && initcalls_done) { > + dev_WARN(dev, "ignoring dependency for device, assuming no driver"); > + return -ENODEV; > + } > + > + return -EPROBE_DEFER; > +} > + > /** > * deferred_probe_initcall() - Enable probing of deferred devices > * > @@ -240,6 +250,13 @@ static int deferred_probe_initcall(void) > /* Sort as many dependencies as possible before exiting initcalls */ > flush_work(&deferred_probe_work); > initcalls_done = true; > + > + /* > + * Trigger deferred probe again, this time we won't defer anything > + * that is optional > + */ > + driver_deferred_probe_trigger(); > + flush_work(&deferred_probe_work); > return 0; > } > late_initcall(deferred_probe_initcall); > diff --git a/include/linux/device.h b/include/linux/device.h > index 477956990f5e..f3dafd44c285 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -334,6 +334,8 @@ struct device *driver_find_device(struct device_driver *drv, > struct device *start, void *data, > int (*match)(struct device *dev, void *data)); > > +int driver_deferred_probe_check_init_done(struct device *dev, bool optional); > + > /** > * struct subsys_interface - interfaces to device functions > * @name: name of the device function > -- > 2.17.0 >
next prev parent reply other threads:[~2018-05-24 22:29 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-24 17:50 [PATCH v2 0/8] Make deferring probe forever optional Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` [PATCH v2 1/8] driver core: make deferring probe after init optional Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 18:18 ` Mark Brown 2018-05-24 18:18 ` Mark Brown 2018-05-24 20:25 ` Rob Herring 2018-05-24 20:25 ` Rob Herring 2018-05-25 11:47 ` Robin Murphy 2018-05-25 11:47 ` Robin Murphy 2018-05-29 5:12 ` Frank Rowand 2018-05-29 5:12 ` Frank Rowand 2018-05-29 14:46 ` Rob Herring 2018-05-29 14:46 ` Rob Herring 2018-05-29 14:46 ` Rob Herring 2018-05-24 18:56 ` Greg Kroah-Hartman 2018-05-24 18:56 ` Greg Kroah-Hartman 2018-05-24 19:42 ` Rob Herring 2018-05-24 19:42 ` Rob Herring 2018-05-24 19:00 ` Greg Kroah-Hartman 2018-05-24 19:00 ` Greg Kroah-Hartman 2018-05-24 20:57 ` Rob Herring 2018-05-24 20:57 ` Rob Herring 2018-05-25 12:20 ` Robin Murphy 2018-05-25 12:20 ` Robin Murphy 2018-05-25 17:35 ` Rob Herring 2018-05-25 17:35 ` Rob Herring 2018-05-24 22:28 ` Bjorn Andersson [this message] 2018-05-24 22:28 ` Bjorn Andersson 2018-05-24 23:47 ` Rob Herring 2018-05-24 23:47 ` Rob Herring 2018-05-24 17:50 ` [PATCH v2 2/8] driver core: add a deferred probe timeout Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 19:01 ` Greg Kroah-Hartman 2018-05-24 19:01 ` Greg Kroah-Hartman 2018-05-24 19:45 ` Rob Herring 2018-05-24 19:45 ` Rob Herring 2018-05-24 19:51 ` Greg Kroah-Hartman 2018-05-24 19:51 ` Greg Kroah-Hartman 2018-05-24 17:50 ` [PATCH v2 3/8] dt-bindings: pinctrl: add a 'pinctrl-use-default' property Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` [PATCH v2 4/8] arm: dts: bcm283x: mark the UART pin muxing nodes with pinctrl-use-default Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` [PATCH v2 5/8] pinctrl: optionally stop deferring probe at end of initcalls Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-30 7:00 ` Linus Walleij 2018-05-30 7:00 ` Linus Walleij 2018-05-30 7:00 ` Linus Walleij 2018-05-24 17:50 ` [PATCH v2 6/8] iommu: Stop " Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` Rob Herring [not found] ` <20180524175024.19874-1-robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-05-24 17:50 ` [PATCH v2 7/8] iommu: Remove IOMMU_OF_DECLARE Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-24 17:50 ` Rob Herring [not found] ` <20180524175024.19874-8-robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 2018-05-25 11:31 ` Will Deacon 2018-05-25 11:31 ` Will Deacon 2018-05-25 11:31 ` Will Deacon 2018-05-28 6:53 ` Marek Szyprowski 2018-05-28 6:53 ` Marek Szyprowski 2018-05-28 6:53 ` Marek Szyprowski 2018-05-24 17:50 ` [PATCH v2 8/8] PM / Domains: Stop deferring probe at the end of initcall Rob Herring 2018-05-24 17:50 ` Rob Herring 2018-05-29 11:48 ` [PATCH v2 0/8] Make deferring probe forever optional Joerg Roedel 2018-05-29 11:48 ` Joerg Roedel
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