[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 #33 from Alan Stern (stern@rowland.harvard.edu) ---
Created attachment 308614
  --> https://bugzilla.kernel.org/attachment.cgi?id=308614&action=edit
Add a configurable delay before reset-resumes

As far as I can tell, the card reader disconnects from the Samsung system
_every_ time you go through a suspend/resume cycle.  For example, in the usbmon
trace you attached to comment #9, where the reader worked after the resume,
there was a disconnect and reconnect.  You may not be aware of them because
they are hidden by the usb-persist mechanism.

And by the way, these disconnects are not "software simulated".  They are real,
honest-to-goodness disconnections.  Yes, the disconnection is only electrical,
not physical (the wires remain attached), but as far as the computer hardware
is concerned there is no difference.

In any case, you can try the attached patch.  It adds a delay before every
reset-resume, and you can set the length of the delay (in milliseconds) by
writing to the /sys/module/usbcore/parameters/reset_resume_delay file.

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