Re: [PATCH] OF: mark released devices as no longer populated

[Russell King - ARM Linux <linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>]

Ping, this issue still exists with 4.11-rc4 - and there's been no
reaction from the alleged CAAM maintainers.

On Tue, Aug 09, 2016 at 11:48:38AM -0500, Rob Herring wrote:
> On Tue, Aug 9, 2016 at 4:33 AM, Russell King <rmk+kernel-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org> wrote:
> > When a Linux device is released and cleaned up, we left the OF device
> > node marked as populated.  This causes the Freescale CAAM driver
> > (drivers/crypto/caam) problems when the module is removed and re-
> > inserted:
> >
> > JR0 Platform device creation error
> > JR0 Platform device creation error
> > caam 2100000.caam: no queues configured, terminating
> > caam: probe of 2100000.caam failed with error -12
> >
> > The reason is that CAAM creates platform devices for each job ring:
> >
> >         for_each_available_child_of_node(nprop, np)
> >                 if (of_device_is_compatible(np, "fsl,sec-v4.0-job-ring") ||
> >                     of_device_is_compatible(np, "fsl,sec4.0-job-ring")) {
> >                         ctrlpriv->jrpdev[ring] =
> >                                 of_platform_device_create(np, NULL, dev);
> >
> > which sets OF_POPULATED on the device node, but then it cleans these
> > up:
> >
> >         /* Remove platform devices for JobRs */
> >         for (ring = 0; ring < ctrlpriv->total_jobrs; ring++) {
> >                 if (ctrlpriv->jrpdev[ring])
> >                         of_device_unregister(ctrlpriv->jrpdev[ring]);
> 
> This looks a bit asymmetrical to me with a of_platform_device_* call
> and a of_device_* call.
> 
> I think you could use of_platform_{de}populate here instead. That
> would simplify things in the driver a bit too as you wouldn't need to
> store jrpdev. It wouldn't work if there are other child nodes with
> compatible strings which you don't want devices created.
> 
> >         }
> >
> > which leaves OF_POPULATED set.
> >
> > Arrange for platform devices with a device node to clear the
> > OF_POPULATED bit when they are released.
> >
> > Signed-off-by: Russell King <rmk+kernel-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>
> > ---
> > Please check this carefully - it may have issues where an of_node
> > pointer is copied from one platform device to another, but IMHO
> > doing that is itself buggy behaviour.
> 
> Agreed, that is wrong.
> 
> >
> > Resending due to wrong list address, sorry.
> >
> >  include/linux/of_device.h | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/include/linux/of_device.h b/include/linux/of_device.h
> > index cc7dd687a89d..7a8362d0c6d2 100644
> > --- a/include/linux/of_device.h
> > +++ b/include/linux/of_device.h
> > @@ -43,6 +43,7 @@ extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env
> >
> >  static inline void of_device_node_put(struct device *dev)
> >  {
> > +       of_node_clear_flag(dev->of_node, OF_POPULATED);
> 
> This would result in clearing the flag twice in the
> of_platform_populate/of_platform_depopulate case. It would do the same
> for other bus types like i2c as well. That doesn't really hurt
> anything that I can think of, but just not the best implementation. I
> think adding a of_platform_device_unregister() call that wraps
> of_platform_device_destroy would be more balanced.
> 
> I looked thru all the callers of of_platform_device_create. The only
> other ones affected by this are:
> 
> drivers/macintosh/ams/ams-core.c
> drivers/macintosh/therm_adt746x.c
> drivers/macintosh/therm_windtunnel.c
> 
> The others either have no remove path or a buggy remove path.
> 
> Rob

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