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MUSB interrupt storm on device removal

PATCH Bin Liu 1 participant 1 message Jan 22, 2019

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Bin Liu

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Hi Johan,

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Hi,

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I have a strange problem with the musb driver in host mode on AM3358 (beaglebone) hardware. If I connect a multi-port serial adapter and

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Is this on beaglebone or beagleboneblack?

We've seen it with Beaglebone Enhanced [1] and BeagleCore [2] based devices. Both are based on the AM3358 and mostly compatible with the Beaglebone Black.

[1] https://elinux.org/SanCloud_BeagleBoneEnhanced
[2] http://beaglecore.com/products/bcm1str.html

Quoted 8 lines

Okay, now I see you have a hub on the board. I just reproduced the console lockup after added a hub in my setup. I will find some time to debug this.

FYI, there was a similar issue in a few years ago, which was that the hub routine never got called during the storm then the device disconnect event never got populated from the hub driver. I am wondering if this is the same issue pops up again...

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Now that you mentioned the hub, I tried connecting the serial adapter to the OTG port (in host mode) on the Beaglebone Enhanced (it's not normally used in this product). When connected directly, the disconnect indeed works properly. With a hub in between, it breaks.

Please use the following hack as a workaround for now. I will think more about it.

Regards,
-Bin.

--------8<----------
diff git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c index b59ce9ad14ce..3719f6d9b26c 100644

drivers/usb/musb/musb_host.c void musb_host_rx(struct musb *musb, u8 epnum) · line 1817

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drivers/usb/musb/musb_host.c +1 -1
@@ -1811,7 +1811,7 @@ void musb_host_rx(struct musb *musb, u8 epnum)
        } else if (rx_csr & MUSB_RXCSR_H_ERROR) {
                musb_dbg(musb, "end %d RX proto error", epnum);
 
-               status = -EPROTO;
+               status = -EPIPE;
                musb_writeb(epio, MUSB_RXINTERVAL, 0);
 
                rx_csr &= ~MUSB_RXCSR_H_ERROR;

When a usb serial device is detached, the musb controller driver returns -EPROTO in urb giveback, then usb_serial_generic_read_bulk_callback() re-submit the urb, this circle causes interrupt storm, and the hub driver workqueue never got a chance to run to populate the device disconnect event, the whole console locks up. Do you think usb_serial_generic_read_bulk_callback() should handle -EPROTO as well?

Regards,
-Bin.

drivers/usb/serial/generic.c +1 -0
index 2274d9625f63..8c2a6e55de3a 100644
@@ -397,6 +397,7 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb)
                                                        __func__, status);
                return;
        case -EPIPE:
+       case -EPROTO:
                dev_err(&port->dev, "%s - urb stopped: %d\n",
                                                        __func__, status);
                return;