On Wed, Oct 31, 2012 at 3:07 PM, Pantelis Antoniou
<panto@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Oct 31, 2012, at 11:55 PM, Russ Dill wrote:
>
>> On Wed, Oct 31, 2012 at 9:52 AM, Pantelis Antoniou
>> <panto@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>> Introducing capebus; a bus that allows small boards (capes) to connect
>>> to a complex SoC using simple expansion connectors.
>>>
>
> [snip]
>>> + if (drv) {
>>> + /* call the removed bus method (if added prev.) */
>>> + if (cape_dev->added) {
>>> + BUG_ON(cape_dev->bus == NULL);
>>> + BUG_ON(cape_dev->bus->ops == NULL);
>>> + if (cape_dev->bus->ops->dev_removed)
>>> + cape_dev->bus->ops->dev_removed(cape_dev);
>>> + cape_dev->added = 0;
>>> + }
>>
>> Is there any case where added will not track drv?
>
>
> Yes, there is a corner case here.
>
> There is the case where while the device is created there is no matching
> driver yet. Either that's the case of a not supported cape, or the
> cape driver hasn't been loaded yet.
>
> We do need the device to be created, so that the user can browse in the
> sysfs it's eeprom attributes.
>
> There's some further complications with runtime cape overrides, but
> that's the gist of it.
I'm trying to figure out how that would come about, here is where
added is set to 1:
+ /* all is fine... */
+ cape_dev->driver = drv;
+ cape_dev->added = 1;
This is after calling drv->probe, so drv is not null.
There is a brief time here where added is 0, but driver is not.
+ if (drv) {
+ /* call the removed bus method (if added prev.) */
+ if (cape_dev->added) {
+ BUG_ON(cape_dev->bus == NULL);
+ BUG_ON(cape_dev->bus->ops == NULL);
+ if (cape_dev->bus->ops->dev_removed)
+ cape_dev->bus->ops->dev_removed(cape_dev);
+ cape_dev->added = 0;
+ }
+ if (drv->remove) {
+ pm_runtime_get_sync(dev);
+ drv->remove(cape_dev);
+ pm_runtime_put_noidle(dev);
+ }
+ cape_dev->driver = NULL;
Is one of the remove or resume functions check added in this case?
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