On Wed, Apr 23, 2014 at 3:05 PM, Grant Likely <grant.lik...@linaro.org> wrote: > On Mon, 21 Apr 2014 16:05:29 -0500, Rob Herring <robherri...@gmail.com> wrote: >> On Wed, Nov 21, 2012 at 8:44 AM, Grant Likely <grant.lik...@secretlab.ca> >> wrote: >> > The "platform_bus" (note: not platform_bus_type) only exists as an empty >> > directory to put platform devices into. However, it really doesn't make >> > sense to segregate all the platform devices into a sub directory when >> > typically they are memory mapped devices that doen't go through any >> > particular bus. Particularly on embedded type platforms the platform_bus >> > directory doesn't add anything. >> > >> > However, this will probably just end up breaking some userspace that >> > depends on the /sys/devices/platform/ path to be present (no matter how >> > much we protest that userspace must not depend on paths in sysfs). So >> > while I'm seriously proposing this change, it may just be unacceptable >> > ABI breakage >> >> An old thread, but was there ever a conclusion to this? We now have a >> mixture of using platform_bus as the parent or not on various ARM >> platforms. > > We kind of concluded in the opposite direction. Instead of removing the > /sys/device/platform directory, the drivers/of code should be changed to > use it. > > The following patch is sufficient to have the same effect. It doesn't > unify the OF and non-OF paths of platform device addition, but it gets > them closer. I've been nervous about applying it because I'm concerned > about userspace breakage, but maybe it just needs to be merged and we > can quirk out systems that break.
Ugh, no matter what we do, something is going to be inconsistent. With this patch, the platform_devices get moved under /sys/devices/platform, but an amba_device at the top level stays where it is. We could move amba devices under the same hierarchy, but that doesn't seem appropriate. We could have a separate /sys/devices/of hierarchy for generating devices into if this really is a problem that needs to be solved. I'm not convinced that a real problem exists though. PowerPC has been creating the devices directly under /sys/devices at least since 2.6.12. With the DT being hierarchical to begin with, and the dt code preserving the hierarchy, on most platforms there won't be a lot of things at the root. Anyway, whatever. I don't care enough to argue anymore. Move them if you like, but make sure the root AMBA devices get created in the same place. g. > > --- > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > index 404d1daebefa..40a85b85c932 100644 > --- a/drivers/of/platform.c > +++ b/drivers/of/platform.c > @@ -175,7 +175,7 @@ struct platform_device *of_device_alloc(struct > device_node *np, > #if defined(CONFIG_MICROBLAZE) > dev->dev.dma_mask = &dev->archdata.dma_mask; > #endif > - dev->dev.parent = parent; > + dev->dev.parent = parent ? parent : &platform_bus; > > if (bus_id) > dev_set_name(&dev->dev, "%s", bus_id); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
