> >>>> When gadget driver is inserted and OTG is in host mode, interrupts
> >>>> occur which are not handled by chipidea driver causing following
> >>>> problem. To avoid this problem, don't allow insertion of gadget
> >>>> driver in host mode.
> >>>>
> >>>> root@mx6q:~# echo -n host > /sys/kernel/debug/ci_hdrc.0/role
> >>>> root@mx6q:~# modprobe g_ether using random self ethernet address
> >>>> using random host ethernet address
> >>>> usb0: HOST MAC aa:4b:f8:b4:d7:81
> >>>> usb0: MAC 5e:65:a8:9e:6e:45
> >>>> using random self ethernet address
> >>>> using random host ethernet address
> >>>> g_ether gadget: Ethernet Gadget, version: Memorial Day 2008 g_ether
> >>>> gadget: g_ether ready root@mx6q35:~# irq 75: nobody cared (try
> >>>> booting with the "irqpoll" option)
> >>>> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.16.0-rc2-00001-gd675913
> >>>> #53
> >>>> Backtrace:
> >>>> [<80012418>] (dump_backtrace) from [<800126fc>]
> (show_stack+0x18/0x1c)
> >>>> r6:8092bae0 r5:8092bae0 r4:00000000 r3:00000000 [<800126e4>]
> >>>> (show_stack) from [<806770bc>] (dump_stack+0x8c/0xa4) [<80677030>]
> >>>> (dump_stack) from [<80074520>] (__report_bad_irq+0x28/0xc8)
> >>>> r6:0000004b r5:00000000 r4:be00ab00 r3:00000000 [<800744f8>]
> >>>> (__report_bad_irq) from [<80074ae8>] (note_interrupt+0x264/0x2c4)
> >>>> r6:0000004b r5:00000000 r4:be00ab00 r3:00000000 [<80074884>]
> >>>> (note_interrupt) from [<80072400>]
> (handle_irq_event_percpu+0xb4/0x13c)
> >>>> r10:80969dc6 r9:be00ab00 r8:0000004b r7:00000000 r6:00000000
> r5:00000000
> >>>> r4:00000000 r3:00000000
> >>>> [<8007234c>] (handle_irq_event_percpu) from [<800724cc>]
> (handle_irq_event+0x44/0x64)
> >>>> r10:00000000 r9:806816b0 r8:80907f20 r7:0000004b r6:bd882c40
> r5:be00ab5c
> >>>> r4:be00ab00
> >>>> [<80072488>] (handle_irq_event) from [<800758b8>]
> (handle_fasteoi_irq+0xc8/0x1bc)
> >>>> r6:8092bd64 r5:be00ab5c r4:be00ab00 r3:00000000 [<800757f0>]
> >>>> (handle_fasteoi_irq) from [<80071b14>] (generic_handle_irq+0x30/0x44)
> >>>> r6:80906020 r5:80902e2c r4:0000004b r3:800757f0 [<80071ae4>]
> >>>> (generic_handle_irq) from [<8000f3d8>] (handle_IRQ+0x54/0xbc)
> >>>> r4:8090ed2c r3:00000180
> >>>> [<8000f384>] (handle_IRQ) from [<800086cc>]
> (gic_handle_irq+0x30/0x68)
> >>>> r8:00000000 r7:f4000100 r6:80907e28 r5:8090eea0 r4:f400010c
> >>>> r3:000000a0 [<8000869c>] (gic_handle_irq) from [<80013264>]
> >>>> (__irq_svc+0x44/0x5c) Exception stack(0x80907e28 to 0x80907e70)
> >>>> 7e20: 00000001 00000000 00000000 80911f70 00000282
> 80906000
> >>>> 7e40: 8002eec4 0000001d 00000000 806816b0 00000000 80907ebc
> >>>> 00000000 80907e70
> >>>> 7e60: 800663c4 8002e9bc 60000113 ffffffff
> >>>> r7:80907e5c r6:ffffffff r5:60000113 r4:8002e9bc [<8002e8f4>]
> >>>> (__do_softirq) from [<8002eec4>] (irq_exit+0xb8/0x10c)
> >>>> r10:00000000 r9:806816b0 r8:00000000 r7:0000001d r6:80906000
> r5:80902e2c
> >>>> r4:80906000
> >>>> [<8002ee0c>] (irq_exit) from [<8000f3e0>] (handle_IRQ+0x5c/0xbc)
> >>>> r5:80902e2c r4:8090ed2c
> >>>> [<8000f384>] (handle_IRQ) from [<800086cc>]
> (gic_handle_irq+0x30/0x68)
> >>>> r8:80969dc3 r7:f4000100 r6:80907f20 r5:8090eea0 r4:f400010c
> >>>> r3:000000a0 [<8000869c>] (gic_handle_irq) from [<80013264>]
> >>>> (__irq_svc+0x44/0x5c) Exception stack(0x80907f20 to 0x80907f68)
> >>>> 7f20: 00000001 00000001 00000000 80911f70 80906000 8090e98c
> >>>> 8090e938 80969dc3
> >>>> 7f40: 80969dc3 806816b0 00000000 80907f74 00000000 80907f68
> >>>> 8006640c 8000f754
> >>>> 7f60: 20000013 ffffffff
> >>>> r7:80907f54 r6:ffffffff r5:20000013 r4:8000f754 [<8000f72c>]
> >>>> (arch_cpu_idle) from [<80061c7c>] (cpu_startup_entry+0x104/0x16c)
> >>>> [<80061b78>] (cpu_startup_entry) from [<80672258>]
> (rest_init+0xb0/0xd8)
> >>>> r7:808f4c00 r3:00000000
> >>>> [<806721a8>] (rest_init) from [<808b2bec>] (start_kernel+0x33c/0x3a8)
> >>>> r5:8096a000 r4:8090ea30
> >>>> [<808b28b0>] (start_kernel) from [<10008074>] (0x10008074)
> >>>> handlers:
> >>>> [<804456a8>] ci_irq
> >>>> Disabling IRQ #75
> >>>> usb 2-1: new high-speed USB device number 2 using ci_hdrc usb 2-1:
> >>>> device descriptor read/64, error -110 usb 2-1: device descriptor
> >>>> read/64, error -110 usb 2-1: new high-speed USB device number 3
> >>>> using ci_hdrc usb 2-1: device descriptor read/64, error -110 usb
> >>>> 2-1: device descriptor read/64, error -110 usb 2-1: new high-speed
> >>>> USB device number 4 using ci_hdrc usb 2-1: device not accepting
> >>>> address 4, error -110 usb 2-1: new high-speed USB device number 5
> >>>> using ci_hdrc usb 2-1: device not accepting address 5, error -110
> >>>> usb usb2-port1: unable to enumerate USB device usb 2-1: new
> >>>> full-speed USB device number 6 using ci_hdrc usb 2-1: device
> >>>> descriptor read/64, error -110 usb 2-1: device descriptor read/64,
> >>>> error -110 usb 2-1: new full-speed USB device number 7 using
> >>>> ci_hdrc usb 2-1: device descriptor read/64, error -110 usb 2-1:
> >>>> device descriptor read/64, error -110 usb 2-1: new full-speed USB
> >>>> device number 8 using ci_hdrc usb 2-1: device not accepting address
> >>>> 8, error -110 usb usb2-port1: cannot reset (err = -32) usb
> >>>> usb2-port1: cannot reset (err = -32) usb usb2-port1: cannot reset
> >>>> (err = -32) usb usb2-port1: cannot reset (err = -32) usb
> >>>> usb2-port1: cannot reset (err = -32) usb usb2-port1: Cannot enable.
> >>>> Maybe the USB cable is bad?
> >>>> usb usb2-port1: unable to enumerate USB device
> >>>>
> >>>> Signed-off-by: Abbas Raza <abbas_r...@mentor.com>
> >>>> ---
> >>>> drivers/usb/chipidea/udc.c | 6 ++++++
> >>>> 1 file changed, 6 insertions(+)
> >>>>
> >>>> diff --git a/drivers/usb/chipidea/udc.c
> >>>> b/drivers/usb/chipidea/udc.c index 69425b3..7a12d13 100644
> >>>> --- a/drivers/usb/chipidea/udc.c
> >>>> +++ b/drivers/usb/chipidea/udc.c
> >>>> @@ -1633,6 +1633,12 @@ static int ci_udc_start(struct usb_gadget
> *gadget,
> >>>> unsigned long flags;
> >>>> int retval = -ENOMEM;
> >>>> + if (ci->role == CI_ROLE_HOST) {
> >>>> + dev_err(ci->dev, "error: cannot register gadget driver
> in host"
> >>>> +
> >>>> "mode\n");
> >>>> + return -EPERM;
> >>>> + }
> >>>> +
> >>>> if (driver->disconnect == NULL)
> >>>> return -EINVAL;
> >>>> --
> >>>> 1.8.3.2
> >>>>
> >>> Hi Abbas, I can't reproduce it no matter current role is host or
> >>> peripheral with GregKH's latest usb next.
> >>>
> >>> The reason for it : the controller switches to device mode when it
> >>> is working at host mode, have a check for ci->vbus_active please (at
> >>> ci_udc_start), it should not be true when load usb gadget driver at
> host mode.
> >>>
> >> Hi Peter,
> >>
> >> Actually the steps to reproduce (can be see below) it are not
> >> straight forward but some user can run these steps and get into
> >> issues. Please have a look.
> >>
> >> Steps to reproduce this issue:
> >> 1) boot target (imx6 board) which is connected to a usb host using
> >> OTG cable. Target's OTG port will be in gadget mode after boot.
> >> 2) now switch OTG role to host
> >> 3) modprobe g_ether
> >> 4) you will see the backtrace (unhandled interrupts)
> > Thanks, Abbas.
> >
> > But we do need to support load gadget driver when we at host mode,
> > assume it is at host mode during boots up, and the initialization
> > script will load gadget driver, if it fails to load, the gadget can't
> > work when the user switch ID cable to Micro-B cable which is connected
> to pc.
> >
> > The support for switching role through /sys entry is not well for
> > current chipidea driver, the well supported are:
> > - role switch through id pin (the connection is not there)
> > - role switch through otg fsm (the connection is there)
>
> Right.
>
> > I will try to add solution for switching role without depending on id
> > pin (through /sys entry) for non otg fsm solution.
> >
> What do you mean by 'switching role without depending on id pin'?
Oh, I should use "improve", not add.
We can use both host and peripheral mode without ID cable, switch it
through sys entry like you mention below, but currently, it has bug
you mentioned and some limitations.
For example:
After finishing the step 1-4 (considering the bug has fixed), the user
can switch to device mode through sys enter, but it will not succeed due
to vbus has not changed, it will not call usb_gadget_vbus_connect.
For an improved solution, we can:
- switch role without connection, yes, it has finished now.
- switch role with connection, eg
with B port to pc, we can switch host<-->device
with A port to pc, we can switch host<-->device
Patch is welcome :)
Peter
> I think
> this is already supported because /sys/kernel/debug/ci_hdrc.0/role file
> switches role without caring about the id pin status.
> Or do you want to add an option to disable id pin based role switching?
> Please clarify
>
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