USB card reader problem

[Tony Baechler]

Hi all,

I'm wondering if this is a hardware problem or if I'm doing something wrong. 
  It isn't a big issue, but it has been annoying me for a few years now and 
is more a matter of curiosity.

I have a multiboot setup here.  On sda1, I have Windows XP.  On sda2, I have 
a new install of Ubuntu MATE 15.04.  On sda3, I have Debian testing with 
kernel 2.6.32.  Newer kernels don't support my serial device.

If I turn on the machine and plug in my USB card reader with an SD card 
inserted before the machine boots, the kernel usually sees it and outputs a 
message recognizing it.  I can mount it as normal, copy files to it, etc. 
Most of the time, copying files is fast.  It takes a few seconds to copy 100 
MB.  Obviously it doesn't write to the card that fast because there is a 
long delay when I unmount it.  The same process takes about 10 minutes on 
Windows.

Every once in a while, especially if the system is already booted before I 
plug in the card reader, it's very slow.  It's at least as slow as Windows. 
  If I plug in the reader before the system boots, that usually doesn't 
happen.  Thinking it might be a kernel problem since 2.6.32 is very old, I 
thought I would try with Ubuntu MATE and kernel 3.19.  I had the same 
problem.  It was immediately recognized, but copying from the console was 
very slow.  Thinking it might have to do with the desktop automounting it, I 
unmounted it from the console and remounted it temporarily under /opt. 
There was no improvement.

Every once in a while, I get a strange error message.  I don't have the log 
at the moment, but it says hub 1 port 4 is not responding or some such, but 
it recognizes the card anyway.  Running fsck.vfat shows no errors.  Doing a 
Google search indicates this might have to do with AHCI and newer kernels 
fixed the problem, but as described above, the slowness still happens in 3.19.

Is this a problem with my USB port, my card reader or some other hardware 
problem?  Should I pass something on the kernel command line?  Other 
external drives don't exhibit this behavior, but it happens on many 
different SD cards.  For what it's worth, I've noticed brand new cards with 
nothing on them seem to have the problem more often, but formatting them 
sometimes helps.  Similarly, if I unplug the reader and plug it in again, I 
get the strange error message and slow behavior.  I have two front USB ports 
and it doesn't seem to matter which one I use.

As I mentioned, it isn't a big problem, but it would be nice to figure out 
why it's happening.  Thank you for any suggestions.

--------------------
Tony Baechler, Baechler Access Technology Services
Putting accessibility at the forefront of technology
mailto:bats at batsupport.com
Phone: 1-619-746-8310   Fax: 1-619-449-9898