On Tuesday 16 October 2012 at 12:58:48, Lars-Peter Clausen wrote: > On 10/16/2012 11:43 AM, Lars Poeschel wrote: > > On Tuesday 16 October 2012 at 10:40:26, Lars-Peter Clausen wrote: > >> On 10/12/2012 04:34 PM, Lars Poeschel wrote: > >> Btw. I'm wondering why is the extra platform device required? Can't you > >> not just use the usb device as the parent device for the mfd cells? > > > > This is what I first did, but this does not work. You can read about my > > first thoughts why this is not working here: (To sum it up: The device > > is housed in an usb_device, not a platform_device and This usb_device > > has no mfd_cell member.) > > > > https://lkml.org/lkml/2012/9/28/327 > > > > As I got a bit more deeper I also noticed, that mfd_add_devices > > (obviously) adds the devices "as childs" to the parent device. > > mfd_remove_devices then removes ALL "child" devices from the parent, not > > only those added by mfd_add_devices before. This does not work in the > > case of the usb parent device, because it has other childs that the usb > > layer added before (some endpoints and stuff). So I had to construct an > > "empty" (in sense of childs) mock platform_device between the usb and > > mfd. > > Ah, ok that makes sense. I was a bit confused, because there are other mfd > drivers with for example i2c or spi devices as parents and these work fine, > but I guess this is because non of them registers any additional child > devices. I guess it makes sense to create a mfd cell device type and assign > this type to newly created mfd cells and only unregister a device in > mfd_remove_devices if it has the correct device type. > > E.g. something along the lines of: > > > --- a/drivers/mfd/mfd-core.c > +++ b/drivers/mfd/mfd-core.c > @@ -21,6 +21,10 @@ > #include <linux/irqdomain.h> > #include <linux/of.h> > > +static struct device_type mfd_device_type = { > + .name = "mfd-cell", > +}; > + > int mfd_cell_enable(struct platform_device *pdev) > { > const struct mfd_cell *cell = mfd_get_cell(pdev); > @@ -91,6 +95,7 @@ static int mfd_add_device(struct device *parent, int id, > goto fail_device; > > pdev->dev.parent = parent; > + pdev->dev.type = &mfd_device_type; > > if (parent->of_node && cell->of_compatible) { > for_each_child_of_node(parent->of_node, np) { > @@ -204,10 +209,16 @@ EXPORT_SYMBOL(mfd_add_devices); > > static int mfd_remove_devices_fn(struct device *dev, void *c) > { > - struct platform_device *pdev = to_platform_device(dev); > - const struct mfd_cell *cell = mfd_get_cell(pdev); > + struct platform_device *pdev; > + const struct mfd_cell *cell; > atomic_t **usage_count = c; > > + if (dev->type != &mfd_device_type) > + return 0; > + > + pdev = to_platform_device(dev); > + cell = mfd_get_cell(pdev); > + > /* find the base address of usage_count pointers (for freeing) */ > if (!*usage_count || (cell->usage_count < *usage_count)) > *usage_count = cell->usage_count;
I thought about this and I am not fully happy with it: If we add the mfd devices to the usb_interface parent they are at the same level in the device tree as the usb endpoints and stuff. I would consider this logically wrong. Is this something we should take care of ? -- 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/
