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.
Regards,
John
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