Messages in this thread | | | Date | Wed, 17 Jul 2013 09:17:58 -0700 | From | Greg KH <> | Subject | Re: [linux-sunxi] Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses |
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On Wed, Jul 17, 2013 at 01:46:50PM +0200, Maxime Ripard wrote: > On Mon, Jul 15, 2013 at 11:41:07PM -0700, Greg KH wrote: > > On Mon, Jul 15, 2013 at 11:16:19PM +0200, Oliver Schinagl wrote: > > > So using these new patches for binary attributes, how can I pass data > > > between my driver and the sysfs files using a platform_driver? Or are > > > other 'hacks' needed and using the .groups attribute from > > > platform_driver->device_driver->groups is really the wrong approach. > > > > > > I did ask around and still haven't figured it out so far, so I do > > > apologize if you feel I'm wasting your precious time. > > > > How is the platform device not the same thing that was passed to your > > probe function? > > One thing I don't get here is why it should be set in the > platform_driver structure. From my understanding of the device model, > and since what Oliver is trying to do is exposing a few bytes of memory > to sysfs, shouldn't the sysfs file be attached to the device instead?
It will be created by the driver core for any device attached to the driver automatically.
> I mean, here, the sysfs file will be created under something like > .../drivers/sunxi-sid/eeprom. What happens when you have several > instances of that driver loaded? I'd expect it to have several sysfs > files created, one for each instance. So to me, it should be in the > device structure, not the driver one.
You can't have multiple drivers with the same name loaded (or the same module loaded multiple times.) You can have multiple devices for a single driver, which is what we do all the time.
> Couldn't that be also the reason of Oliver's NULL pointer? If the kobj > is attached to the platform_driver and not to the platform_device, it > should definitely get nasty when we try to cast it and retrieve data > from it (and that would match the different pointers stuff as well.)
No, he's getting a kobject that looks quite different at probe that is different from when the file callback happens, something is odd here...
greg k-h
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