On Thu, 7 Nov 2013, Bin Liu wrote: > 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. A bug in the driver certainly seems more likely than a SETUP packet containing 10 bytes. In any case, STALL is not an allowed response to a SETUP packet. According to section 8.5.3 in the USB-2 spec, the only valid response to a SETUP packet is ACK. If the packet is corrupted, the device has to discard the packet and return no handshake. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
