Re: MIDI gadget allocating too much from coherent pool

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Hi Peter,

On Tue, Sep 22, 2015 at 8:03 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote:
> On Tue, Sep 22, 2015 at 09:07:23AM +0100, Felipe Tonello wrote:
>> On Tue, Sep 22, 2015 at 12:41 AM, Peter Chen <peter.chen@xxxxxxxxxxxxx> wrote:
>> > On Mon, Sep 21, 2015 at 03:25:28PM +0100, Felipe Tonello wrote:
>> >> Hi all,
>> >>
>> >> I actually found the problem but can't really understand. The ci_irq()
>> >> handler (from core.c) is not been called after a ep_queue() from
>> >> f_midi_transmit().
>> >>
>> >> Is there any reason for that?
>> >>
>> >> I used mass_storage gadget, made file transfers and others, and the
>> >> interrupt handler was been called as expected.
>> >>
>> >
>> > Which Soc are you using? And which kernel version are you using?
>>
>> i.MX6Q (industrial temp) and v4.2. We are using the imx6 REX module[1].
>>
>> We checked the errata and didn't seem to have anything relevant.
>>
>> I wonder: was f_midi ever working properly, ie, complete callback ever called?
>>
>
> Would you give your cpu revision number, and show me
> how to reproduce it? I can test at my board.

MCIMX6QAVT10AC

To reproduce:
 * add this line to the f_midi_complete() function under the "case 0":

VDBG(cdev, "%s normal completion (%d), %d/%d\n", ep->name, status,
req->actual, req->length);

 * build a kernel with verbose debug enabled on USB gadget subsystem
 * load g_ether module (this will create an ALSA card and device)
 * connect device to host via usb otg cable.
 * to list the ALSA device, run `amidi -l', use the device listed as "f_midi"
 * send midi message using `amidi -p hw:1,0 -S 901010', my device is
hw:1,0, check the output of amidi -l.
 * run `dmesg'  you should see the message above, but if doesn't then
probably the complete callback wasn't called as well.

OBS: We have set the OTG_ID pin to type B (device), so no need to OTG
cable on our side.

Thanks,

Felipe
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