[Bug 220491] usb_storage connected SD card disconnects/reconnects on resume from suspend

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220491

--- Comment #6 from Alan Stern (stern@rowland.harvard.edu) ---
The usbmon trace is opaque to people who aren't familiar with the USB protocol,
but to people who are, it's a trove of information.

The trace initially shows the card reader getting suspended.  Then during the
resume it shows that the connection was dropped during the suspend (possibly
because the device wasn't powered).  The device gets reset okay, but then
things start to go wrong at this point:

ffff9bbf9f9de0c0 215868796 S Co:3:003:0 s 00 03 0031 0000 0000 0
ffff9bbf9f9de0c0 215872346 C Co:3:003:0 -71 0
ffff9bbf9f9de0c0 215872402 S Co:3:001:0 s 23 03 0018 0004 0000 0
ffff9bbf9f9de0c0 215872413 C Co:3:001:0 0 0
ffff9bbf9f9de0c0 215872539 S Co:3:003:0 s 00 03 0032 0000 0000 0
ffff9bbf9f9de0c0 220976339 C Co:3:003:0 -2 0

The first two lines show the computer telling the device to enable the U2
low-power link state and the device not replying.  The last two lines show the
computer telling the device to enable Latency Tolerance Messages (a part of
Link Power Management) and the device not acknowledging.

This strongly suggests that the device can't handle LPM properly, and it might
start working if you tell the kernel not to use LPM with the device.  You can
do this by adding a parameter to the kernel's boot command line:

   ... usbcore.quirks=05e3:0747:k

where 05e3 and 0747 are the card reader's vendor and product IDs, and 'k' is
the code letter for "No LPM".

-- 
You may reply to this email to add a comment.

You are receiving this mail because:
You are watching the assignee of the bug.