On Thu, May 1, 2014 at 10:26 AM, Grant Likely <grant.likely@xxxxxxxxxx> wrote:
> On Wed, 30 Apr 2014 10:22:25 -0500, Rob Herring <robherring2@xxxxxxxxx> wrote:
>> On Wed, Apr 30, 2014 at 9:05 AM, Pawel Moll <pawel.moll@xxxxxxx> wrote:
>> > In "Device Tree powered" systems, platform devices are usually
>> > massively populated with of_platform_populate() call, executed
>> > at some level of initcalls, either by generic architecture
>> > or by platform-specific code.
>> >
>> > There are situations though where certain devices must be
>> > created (and bound with drivers) before all the others.
>> > This presents a challenge, as devices created explicitly
>> > would be created again by of_platform_populate().
>> >
>> > This patch tries to solve that issue in a generic way,
>> > adding a "populated" flag for a DT node description.
>> > Once set, this device will never be created again via
>> > of_* API, so of_platform_populate() will skip such nodes
>> > (and its children) in a similar way to the non-available
>> > ones.
>> >
>> > Signed-off-by: Pawel Moll <pawel.moll@xxxxxxx>
>>
>> One pondering and one minor change below, otherwise:
>>
>> Acked-by: Rob Herring <robh@xxxxxxxxxx>
>>
>>
>> > ---
>> >
>> > Changes since v1:
>> >
>> > - added of_node_check_and_set_flag()... (atomic test and set)
>> > - ... used it to atomically mark a node...
>> > - ... clearing the bit on error path.
>> >
>> > drivers/of/platform.c | 18 +++++++++++++-----
>> > include/linux/of.h | 7 +++++++
>> > 2 files changed, 20 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>> > index 404d1da..b33927a 100644
>> > --- a/drivers/of/platform.c
>> > +++ b/drivers/of/platform.c
>> > @@ -204,12 +204,13 @@ static struct platform_device *of_platform_device_create_pdata(
>> > {
>> > struct platform_device *dev;
>> >
>> > - if (!of_device_is_available(np))
>> > + if (!of_device_is_available(np) ||
>> > + of_node_check_and_set_flag(np, OF_POPULATED))
>> > return NULL;
>> >
>> > dev = of_device_alloc(np, bus_id, parent);
>> > if (!dev)
>> > - return NULL;
>> > + goto err_clear_flag;
>>
>> I wonder if leaving it set would be the right behavior. I can't see
>> that we would want to process the node again. But this is the
>> exceptional case, so its probably not too important and can stay like
>> this.
>
> That doesn't work in the case where drivers use of_platform_populate().
> MFD devices in particular make use of it. If the driver does not get
> cleared on removal of the devices, then all MFD users will be broken on
> driver unbind/rebind. *
>
> We really need to have the inverse of of_platform_populate which will
> remove all child and child's child devices and clear all flags and such.
> Right now moany drivers are open-coding the removal.
>
> * most drivers are somewhat broken on unbind/rebind anyway, but I don't
> want to make it impossible for a driver to get it right.
The function shouldn't be too difficult. I would expect it to look
something like this. You'll need to check the details.
static int __of_platform_unpopulate_device(struct device *dev, void *c)
{
if (!dev->of_node || !of_node_get_flag(dev->of_node, OF_POPULATED)
return 0;
// recursively remove the children too --- I'd like to find a way
to do this non-recursively
device_for_each_child(dev, NULL, __of_platform_unpopulate_device);
// Need to check if the device should be explicitly unbound from
it's driver before removing it. However, I think the driver core takes
care of this for us.
// Remove based on the bus type
switch (dev->bus) {
case &platform_bus_type:
platform_device_remove(to_platform_device(dev));
break;
case &amba_bus_type:
amba_device_remove(to_platform_device(dev));
break;
}
// Should check here if there are any other children to the
device. It is probably bad to remove a device that still has children.
Need to check what the driver core will do.
}
void of_platform_unpopulate(struct device *parent)
{
device_for_each_child(parent, NULL, __of_platform_unpopulate_device);
}
>
>>
>> >
>> > #if defined(CONFIG_MICROBLAZE)
>> > dev->archdata.dma_mask = 0xffffffffUL;
>> > @@ -227,10 +228,14 @@ static struct platform_device *of_platform_device_create_pdata(
>> >
>> > if (of_device_add(dev) != 0) {
>> > platform_device_put(dev);
>> > - return NULL;
>> > + goto err_clear_flag;
>> > }
>> >
>> > return dev;
>> > +
>> > +err_clear_flag:
>> > + of_node_clear_flag(np, OF_POPULATED);
>> > + return NULL;
>> > }
>> >
>> > /**
>> > @@ -262,14 +267,15 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>> >
>> > pr_debug("Creating amba device %s\n", node->full_name);
>> >
>> > - if (!of_device_is_available(node))
>> > + if (!of_device_is_available(node) ||
>> > + of_node_check_and_set_flag(node, OF_POPULATED))
>> > return NULL;
>> >
>> > dev = amba_device_alloc(NULL, 0, 0);
>> > if (!dev) {
>> > pr_err("%s(): amba_device_alloc() failed for %s\n",
>> > __func__, node->full_name);
>> > - return NULL;
>> > + goto err_clear_flag;
>> > }
>> >
>> > /* setup generic device info */
>> > @@ -309,6 +315,8 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>> >
>> > err_free:
>> > amba_device_put(dev);
>> > +err_clear_flag:
>> > + of_node_clear_flag(node, OF_POPULATED);
>> > return NULL;
>> > }
>> > #else /* CONFIG_ARM_AMBA */
>> > diff --git a/include/linux/of.h b/include/linux/of.h
>> > index 3bad8d1..534cab8 100644
>> > --- a/include/linux/of.h
>> > +++ b/include/linux/of.h
>> > @@ -130,6 +130,12 @@ static inline int of_node_check_flag(struct device_node *n, unsigned long flag)
>> > return test_bit(flag, &n->_flags);
>> > }
>> >
>> > +static inline int of_node_check_and_set_flag(struct device_node *n,
>>
>> Please keep the well known naming convention of the called function:
>> of_node_test_and_set_flag
>
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