Hi,
John Youn <John.Youn@xxxxxxxxxxxx> writes:
> On 3/30/2016 6:22 AM, Felipe Balbi wrote:
>>
>> Hi,
>>
>> John Keeping <john@xxxxxxxxxxxx> writes:
>>> Setting up a gadget with the uac2 function results in:
>>>
>>> Unable to handle kernel NULL pointer dereference at virtual address 00000058
>>> ...
>>> PC is at dwc2_hsotg_irq+0x7f0/0x908
>>> LR is at dwc2_hsotg_irq+0x4c/0x908
>>> Backtrace:
>>> [<c03cd5fc>] (dwc2_hsotg_irq) from [<c00814fc>] (handle_irq_event_percpu+0x130/0x3ec)
>>> [<c00813cc>] (handle_irq_event_percpu) from [<c0081800>] (handle_irq_event+0x48/0x6c)
>>>
>>> In all other loops we already skip endpoints that are null, so do so
>>> here as well.
>>>
>>> Signed-off-by: John Keeping <john@xxxxxxxxxxxx>
>>> ---
>>> drivers/usb/dwc2/gadget.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>>> index 0abf73c..df43ec0 100644
>>> --- a/drivers/usb/dwc2/gadget.c
>>> +++ b/drivers/usb/dwc2/gadget.c
>>> @@ -2606,7 +2606,9 @@ irq_retry:
>>> for (idx = 1; idx < hsotg->num_of_eps; idx++) {
>>> hs_ep = hsotg->eps_in[idx];
>>>
>>> - if (!hs_ep->isochronous || hs_ep->has_correct_parity)
>>> + if (!hs_ep ||
>>> + !hs_ep->isochronous ||
>>> + hs_ep->has_correct_parity)
>>
>> this is fine (even though choice of where to break line is a bit odd),
>> but I have a question about how the rest of the code works (a bit
>> off-topic, sorry)
>>
>>> continue;
>>>
>>> epctl_reg = DIEPCTL(idx);
>>
>> So, this means that the first ISO endpoint without correct parity will
>> be used. Isn't this a bit fragile ? What happens when you use a device
>> with several different interfaces using several different endpoints ?
>>
>> Isn't there a register where we can check which physical endpoint
>> generated the IRQ ? Seems like you really wanna check what:
>>
>
> We discussed this back when the patch was first submitted and
> determined it should work fine like this. I don't remember exactly why
> though.
>
> But this ISOC parity stuff is a workaround and we have a series of
> patches to correctly set up ISOC allowing us to remove it. We're doing
> some final tests before we send them.
fair enough, thanks
--
balbi
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