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Date: Fri, 14 Nov 2014 17:13:23 +0200
From: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
To: Grant Likely <grant.likely@...retlab.ca>
Cc: Rob Herring <robherring2@...il.com>,
Stephen Warren <swarren@...dotorg.org>,
Matt Porter <matt.porter@...aro.org>,
Koen Kooi <koen@...inion.thruhere.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Alison Chaiken <Alison_Chaiken@...tor.com>,
Dinh Nguyen <dinh.linux@...il.com>,
Jan Lubbe <jluebbe@...net.de>,
Alexander Sverdlin <alexander.sverdlin@....com>,
Michael Stickel <ms@...able.de>,
Guenter Roeck <linux@...ck-us.net>,
Dirk Behme <dirk.behme@...il.com>,
Alan Tull <delicious.quinoa@...il.com>,
Sascha Hauer <s.hauer@...gutronix.de>,
Michael Bohan <mbohan@...eaurora.org>,
Ionut Nicu <ioan.nicu.ext@....com>,
Michal Simek <monstr@...str.eu>,
Matt Ranostay <mranostay@...il.com>,
Joel Becker <jlbec@...lplan.org>, devicetree@...r.kernel.org,
Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
linux-kernel <linux-kernel@...r.kernel.org>,
Pete Popov <pete.popov@...sulko.com>,
Dan Malek <dan.malek@...sulko.com>,
Georgi Vlaev <georgi.vlaev@...sulko.com>
Subject: Re: [PATCH v8 4/8] OF: platform: Add OF notifier handler
Hi Grant,
> On Nov 14, 2014, at 01:29 , Grant Likely <grant.likely@...retlab.ca> wrote:
>
> On Tue, 28 Oct 2014 22:36:01 +0200
> , Pantelis Antoniou <pantelis.antoniou@...sulko.com>
> wrote:
>> Add OF notifier handler needed for creating/destroying platform devices
>> according to dynamic runtime changes in the DT live tree.
>>
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
>
> Hi Pantelis,
>
> Some comments below. Feel free to send me fixup patches instead of
> respinning.
>
Sure, I’ll get around to send updated patches over the weekend.
> g.
>
>> ---
>> drivers/base/platform.c | 18 +++++++++--
>> drivers/of/platform.c | 78 +++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/of_platform.h | 10 ++++++
>> 3 files changed, 103 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index b2afc29..282bfec 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -1002,10 +1002,22 @@ int __init platform_bus_init(void)
>>
>> error = device_register(&platform_bus);
>> if (error)
>> - return error;
>> - error = bus_register(&platform_bus_type);
>> + goto err_out;
>> +
>> + error = bus_register(&platform_bus_type);
>> + if (error)
>> + goto err_unreg_dev;
>> +
>> + error = of_platform_register_reconfig_notifier();
>> if (error)
>> - device_unregister(&platform_bus);
>> + goto err_unreg_bus;
>
> We really don't want to fail out here. If the notifier registration fails, it
> doesn't make sense to cause the entire boot to fail.
>
> Instead of refactoring the function, just add the call to
> of_platform_register_reconfig_notifier(), and WARN_ON() failure without
> bailing.
>
> (Actually, you don't need to send me a fixup for this; I've gone ahead
> and fixed it up in my tree)
>
I see. Thanks.
I’m curious under which condition the of_platform_register_reconfig_notifier()
would fail. Only under extreme low memory conditions (and very early in the
boot-sequence). I doubt we’ll get very far - the boot-sequence will croak shortly
after.
>> +
>> + return 0;
>> +err_unreg_bus:
>> + bus_unregister(&platform_bus_type);
>> +err_unreg_dev:
>> + device_unregister(&platform_bus);
>> +err_out:
>> return error;
>> }
>>
>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>> index 3b64d0b..aa8db92 100644
>> --- a/drivers/of/platform.c
>> +++ b/drivers/of/platform.c
>> @@ -546,4 +546,82 @@ void of_platform_depopulate(struct device *parent)
>> }
>> EXPORT_SYMBOL_GPL(of_platform_depopulate);
>>
>> +#ifdef CONFIG_OF_DYNAMIC
>> +
>> +static struct notifier_block platform_of_notifier;
>> +
>> +static int of_platform_notify(struct notifier_block *nb,
>> + unsigned long action, void *arg)
>> +{
>> + struct platform_device *pdev_parent, *pdev;
>> + struct device_node *dn;
>> + int state;
>> + bool children_left;
>> +
>> + state = of_reconfig_get_state_change(action, arg);
>> +
>> + /* no change? */
>> + if (state == -1)
>> + return NOTIFY_OK;
>> +
>> + switch (action) {
>> + case OF_RECONFIG_ATTACH_NODE:
>> + case OF_RECONFIG_DETACH_NODE:
>> + dn = arg;
>> + break;
>> + case OF_RECONFIG_ADD_PROPERTY:
>> + case OF_RECONFIG_REMOVE_PROPERTY:
>> + case OF_RECONFIG_UPDATE_PROPERTY:
>> + dn = ((struct of_prop_reconfig *)arg)->dn;
>> + break;
>> + default:
>> + return NOTIFY_OK;
>> + }
>> +
>> + if (state) {
>> +
>> + /* verify that the parent is a bus */
>> + if (!of_match_node(of_default_bus_match_table, dn->parent))
>> + return NOTIFY_OK; /* not for us */
>
> This doesn't work reliably. Not all callers of of_platform_populate use
> the of_default_bus_match_table. The code needs to actively track the
> nodes that were used to create child devices. We've got a flag in the
> device node now that you can use for that; OF_POPULATED_BUS.
>
I see. That’s a relatively new flag no?
>> +
>> + /* pdev_parent may be NULL when no bus platform device */
>> + pdev_parent = of_find_device_by_node(dn->parent);
>> + pdev = of_platform_device_create(dn, NULL,
>> + pdev_parent ? &pdev_parent->dev : NULL);
>> + of_dev_put(pdev_parent);
>> +
>> + if (pdev == NULL) {
>> + pr_err("%s: failed to create for '%s'\n",
>> + __func__, dn->full_name);
>> + /* of_platform_device_create tosses the error code */
>> + return notifier_from_errno(-EINVAL);
>> + }
>> +
>> + } else {
>> +
>> + /* find our device by node */
>> + pdev = of_find_device_by_node(dn);
>> + if (pdev == NULL)
>> + return NOTIFY_OK; /* no? not meant for us */
>> +
>> + /* unregister takes one ref away */
>> + of_platform_device_destroy(&pdev->dev, &children_left);
>> +
>> + /* and put the reference of the find */
>> + of_dev_put(pdev);
>> +
>> + }
>> +
>> + return NOTIFY_OK;
>> +}
>> +
>> +int of_platform_register_reconfig_notifier(void)
>> +{
>> + platform_of_notifier.notifier_call = of_platform_notify;
>> + return of_reconfig_notifier_register(&platform_of_notifier);
>> +}
>> +EXPORT_SYMBOL_GPL(of_platform_register_reconfig_notifier);
>> +
>> +#endif
>> +
>> #endif /* CONFIG_OF_ADDRESS */
>> diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
>> index c2b0627..01fe5d6 100644
>> --- a/include/linux/of_platform.h
>> +++ b/include/linux/of_platform.h
>> @@ -84,4 +84,14 @@ static inline int of_platform_populate(struct device_node *root,
>> static inline void of_platform_depopulate(struct device *parent) { }
>> #endif
>>
>> +#ifdef CONFIG_OF_DYNAMIC
>> +extern int of_platform_register_reconfig_notifier(void);
>> +#else
>> +static inline int of_platform_register_reconfig_notifier(void)
>> +{
>> + return 0;
>> +}
>> +#endif
>> +
>> +
>> #endif /* _LINUX_OF_PLATFORM_H */
>> --
>> 1.7.12
--
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