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: $ 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.lik...@linaro.org> > Cc: Rob Herring <robh...@kernel.org> > Cc: Arnd Bergmann <a...@arndb.de> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> > --- > 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); > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
