USB card reader problem

[J.Witvliet at mindef.nl]

Hi Tony,

I've likewise behaviour: copying (or rsyncing) goes too fast, obviously buffering.
When umounting, or doing the sync command, you'll get the expected delay.

One can avoid that, by adding the "-o sync"option when mounting.
Then copying itself will be slow ;-)

Hw


-----Original Message-----
From: ubuntu-users-bounces at lists.ubuntu.com [mailto:ubuntu-users-bounces at lists.ubuntu.com] On Behalf Of Tony Baechler
Sent: vrijdag 14 augustus 2015 10:57
To: Ubuntu user technical support, not for general discussions
Subject: Re: USB card reader problem

I'm sending this again because I remembered something.  I have, in fact, tried the card reader on a different machine.  It didn't exhibit the odd behavior and the other machine was always on.  Also, I made note of the exact error message from kernel 2.6.32:

Cannot enumerate USB device on port 3

Doing a Google search, this would indicate a kernel issue, but as I mentioned, 3.19 does the same thing.  Another thing that's odd is sometimes when I plug in the card reader and boot the machine, the kernel doesn't see it at all.  If I unplug it and plug it in again, I get the above error but the kernel finds it immediately.  After it gives the error, it says device sdd found, assuming cache: write through.  I can always reproduce the very slow write speed after the error message and I almost never have the problem if the error message isn't displayed.

As another random piece of information, I installed kexec-tools and using it to reboot into the already running 2.6.32 kernel seems to not show the error even when the reader has been plugged in for several hours.

On 8/13/2015 2:29 AM, Petter Adsen wrote:
> On Thu, 13 Aug 2015 01:56:08 -0700
> Tony Baechler <bats at batsupport.com> wrote:
>> 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.
>
> Do you have the option of trying the card reader in another machine, 
> and/or trying another card reader on this machine? As a first instinct 
> I would be suspicious of the reader, or maybe the cable, if other USB 
> devices work fine.

Actually, this problem happened with my old card reader, so I replaced it, thinking that might be the problem.  The new reader seems better if I plug it in before the system boots, but otherwise there is no obvious difference. 
  The readers are different brands.  I don't have a different machine.  I'm not sure what cable you mean as the reader plugs directly into the USB port.

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