Messages in this thread | | | Subject | Re: [PATCH v7 4/4] usb: gadget: udc-core: independent registration of gadgets and gadget drivers | From | Marek Szyprowski <> | Date | Tue, 24 Nov 2015 13:38:15 +0100 |
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Hello,
On 2015-11-23 16:32, Alan Stern wrote: > On Mon, 23 Nov 2015, Marek Szyprowski wrote: > >> From: Ruslan Bilovol <ruslan.bilovol@gmail.com> >> >> Change behavior during registration of gadgets and >> gadget drivers in udc-core. Instead of previous >> approach when for successful probe of usb gadget driver >> at least one usb gadget should be already registered >> use another one where gadget drivers and gadgets >> can be registered in udc-core independently. >> >> Independent registration of gadgets and gadget drivers >> is useful for built-in into kernel gadget and gadget >> driver case - because it's possible that gadget is >> really probed only on late_init stage (due to deferred >> probe) whereas gadget driver's probe is silently failed >> on module_init stage due to no any UDC added. >> >> Also it is useful for modules case - now there is no >> difference what module to insert first: gadget module >> or gadget driver one. >> >> Tested-by: Maxime Ripard <maxime.ripard@free-electrons.com> >> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com> >> [simplified code as requested by Alan Stern and Felipe Balbi, >> fixed checkpatch issues] >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> >> Tested-by: Peter Chen <peter.chen@freescale.com> > I missed this the last time through... > >> @@ -403,6 +408,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget, >> usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED); >> udc->vbus = true; >> >> + /* pick up one of pending gadget drivers */ >> + list_for_each_entry(driver, &gadget_driver_pending_list, pending) { >> + if (!driver->udc_name || strcmp(driver->udc_name, >> + dev_name(&udc->dev)) == 0) { >> + ret = udc_bind_to_driver(udc, driver); >> + if (ret) >> + goto err4; >> + list_del(&driver->pending); > This has to be list_del_init(). And somewhere in > usb_gadget_probe_driver() you need to do > INIT_LIST_HEAD(&driver->pending). > >> @@ -577,6 +596,10 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver) >> break; >> } >> >> + if (ret) { >> + list_del(&driver->pending); > Otherwise this will cause a crash or corrupt some random area of > memory.
'pending' handle is added to gadget_driver_pending_list in usb_gadget_probe_driver(), then when udc is available it is removed from this list and bound to the given driver. In usb_gadget_unregister_driver() the gadget is either unbound from the udc or if is was not bound to any udc, removed from pending list. I see no need for adding INIT_LIST_HEAD.
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
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