On Tue, 18 Nov 2014 11:36:19 +0100 , Andrzej Hajda <a.hajda@xxxxxxxxxxx> wrote: > On 11/04/2014 11:45 AM, Grant Likely wrote: > > Currently the devices created by drivers/of/platform.c get created at > > the root of /sys/devices. This goes against the typical pattern for > > sysfs where the top level /sys/devices structure contains categories of > > devices, and the structure of devices is placed below that. To fix this, > > make the code in drivers/of/platform.c follow the drivers/base/platform.c > > behaviour, and use &platform_bus as the default parent for all new > > platform_devices and amba_devices. > > > > This change has been discussed for a long time, but nobody has actually > > acted on it. Userspace code that expects to find devices under a fixed > > /sys/devices/... path will be affected. It isn't /supposed/ to do that, > > but if anyone complains then I'll add a default-off workaround option to > > put them back into the root. > > One of side effects of this change is that platform drivers registering > other platform drivers or devices in their probe callback can deadlock > due to double device_lock on platform device. This is for example case > of exynos_drm driver[1]. I guess it could/should be fixed in exynos_drm. > Anyway it can affect other drivers as well. At least grep shows few > possible candidates: What on earth is that driver doing registering additional drivers in the probe hook?!? That's madness, and should be treated as a bug. g. > > $ git grep -p platform_driver_register | grep -A1 -P '_probe\(struct > platform_device' > > drivers/gpu/drm/exynos/exynos_drm_drv.c=static int > exynos_drm_platform_probe(struct platform_device *pdev) > drivers/gpu/drm/exynos/exynos_drm_drv.c: ret = > platform_driver_register(&fimd_driver); > -- > drivers/gpu/drm/sti/sti_drm_drv.c=static int > sti_drm_platform_probe(struct platform_device *pdev) > drivers/gpu/drm/sti/sti_drm_drv.c: > platform_driver_register(&sti_drm_master_driver); > -- > drivers/mtd/nand/atmel_nand.c=static int atmel_nand_probe(struct > platform_device *pdev) > drivers/mtd/nand/atmel_nand.c: res = > platform_driver_register(&atmel_nand_nfc_driver); > > > [1]: http://permalink.gmane.org/gmane.comp.video.dri.devel/117727 > > Regards > Andrzej > > > > > > Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxx> > > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > > Cc: Arnd Bergmann <arnd@xxxxxxxx> > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > > --- > > drivers/of/platform.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > > index 3b64d0bf5bba..7c6771986c06 100644 > > --- a/drivers/of/platform.c > > +++ b/drivers/of/platform.c > > @@ -138,7 +138,7 @@ struct platform_device *of_device_alloc(struct device_node *np, > > } > > > > dev->dev.of_node = of_node_get(np); > > - dev->dev.parent = parent; > > + dev->dev.parent = parent ? : &platform_bus; > > > > if (bus_id) > > dev_set_name(&dev->dev, "%s", bus_id); > > @@ -291,7 +291,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node, > > > > /* setup generic device info */ > > dev->dev.of_node = of_node_get(node); > > - dev->dev.parent = parent; > > + dev->dev.parent = parent ? : &platform_bus; > > dev->dev.platform_data = platform_data; > > if (bus_id) > > dev_set_name(&dev->dev, "%s", bus_id); > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
