Re: musb driver bug?

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On Thu, Nov 7, 2013 at 12:01 PM, Felipe Balbi <balbi@xxxxxx> wrote:
> Hi,
>
> On Thu, Nov 07, 2013 at 11:54:48AM -0600, Bin Liu wrote:
>> I am debugging a weird musb problem in which musb is in high-speed
>> device mode loaded with g_mass_storage. For some reason, musb received
>> 10 bytes in SETUP packets during enumeration. Please see the following
>> log from musb.
>>
>> <after connected to host>
>> [ 447.100858] musb-hdrc musb-hdrc.0: usbintr (1) epintr(0)
>> [ 447.250856] musb-hdrc musb-hdrc.0: usbintr (4) epintr(0)
>> [ 447.569139] musb-hdrc musb-hdrc.0: usbintr (0) epintr(1)
>> [ 447.574515] musb_g_ep0_irq 720: SetupEnd came in a wrong ep0stage setup
>> [ 447.581189] musb_g_ep0_irq 815: SETUP packet len 10 != 8 ?
>> [ 447.586737] musb-hdrc musb-hdrc.0: usbintr (0) epintr(1)
>> [ 447.592103] musb_g_ep0_irq 815: SETUP packet len 10 != 8 ?
>> [ 447.597652] musb-hdrc musb-hdrc.0: Unhandled USB IRQ 00000001-00000000
>> ......
>>
>> When look at the following code in musb_gadget_ep0.c, when len != 8,
>> musb_read_setup() is not called, so it just breaks out without
>> flushing the fifo or sending
>> MUSB_CSR0_P_SVDRXPKTRDY. Is this a bug? I would think in this error
>
> in a sense, yes. OTOH, a setup packet with less than 8 bytes is a much
> larger bug on the host side, right ? Still, I think that you should
> reply with a stall in that case.

I am in the early stage of the investigation, there are still many
things I need to check, but I am guessing the 10-byte SETUP issue is
due to signal integrity. The device chip (musb) and the host chip are
on the same board, DP/DM are directly wired together (that is why I
cannot hook up an analyzer yet).

I just came across to this portion of the code, and was wondering this
is a bug in the driver which does not handle this corner case
properly. Thanks for the confirmation.

-Bin.

>
> --
> balbi
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