From mboxrd@z Thu Jan 1 00:00:00 1970 From: laurent.pinchart@ideasonboard.com (Laurent Pinchart) Date: Tue, 14 Feb 2017 15:46 +0200 Subject: [BUG] usb: gadget: Kernel oops with UVC USB gadget and configfs In-Reply-To: <87r331zy73.fsf@belgarion.home> References: <497c3c61-31f0-4d40-9bab-5a0aa793e5e9@tul.cz> <840f1745-8792-9d7b-9f43-961614b6938d@tul.cz> <87r331zy73.fsf@belgarion.home> Message-ID: <2813264.gunpljLm9f@avalon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Robert, On Monday 13 Feb 2017 20:29:36 Robert Jarzmik wrote: > Petr Cvek writes: > > Dne 12.2.2017 v 13:02 Robert Jarzmik napsal(a): > > That's weird I even removed pxa_set_udc_info() from magician machine init > > and it still fails. Host cable and/or actual camera is not required. It > > fails without them. > > > > So you binded pxa27x-udc as UDC controller (= activated it) and then > > rmmoded it and nobody complained? > > No, that usecase actually fails. I think you could submit a proper patch > with the diff in [1], with which the pxa27x-udc unloading will work. > > But it's not _your_ testcase, as per your provided callstack : > [ 2152.826529] [] (udc_bind_to_driver [udc_core]) from > [] (usb_add_gadget_udc_release+0x138/0x21c [udc_core]) [ > 2152.826731] [] (usb_add_gadget_udc_release [udc_core]) from > [] (pxa_udc_probe+0x290/0x2fc [pxa27x_udc]) [ 2152.833554] > [] (pxa_udc_probe [pxa27x_udc]) from [] > (platform_drv_probe+0x38/0x84) [ 2152.833602] [] > (platform_drv_probe) from [] (driver_probe_device+0x1e0/0x3f4) > > Your problem seems in the pxa_udc_probe(), which I would presume you're > doing for a second time, ie. after modprobe pxa27x_udc + bind UDC > controller + rmmod pxa27x_udc + modprobe pxa27x_udc. > > I suspect that in this case, the problem is that the rmmod works while udc > is still bound to the composite. The lsmod seems to prove that the refcount > is still 0 while usb_f_uvc is is bound to pxa27x_udc. > > [@Felipe and @Laurent] > I have no knowledge of usb_f_uvc, so would you tell me if binding usb_f_uvc > to pxa27_udc should have incremented the module refcount of pxa27x_udc or > not ? I'm not familiar with how modules refcount is handled in the USB gadget framework, that's more a question for Felipe. I don't think the problem is specific to usb_f_uvc, all gadget drivers should behave the same way (and if they don't that should be fixed). > > Can you try v4.10? Or send me exact commit on what you tested it so I can > > test it too. > > My top commit (not counting yours) is : 61c04572de40 ("Merge branch 'for-rc' > of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux") -- Regards, Laurent Pinchart