Re: Mainpine IQ Express Rev3 problems beginning 2.6.36

[Greg KH <greg@kroah.com>]

On Wed, Dec 08, 2010 at 03:55:29PM -0800, Lee Howard wrote:
> Hello everyone,
> 
> A week ago I had a customer report to me that they were having
> problems using the Mainpine IQ Express Rev3 (multiport modem which
> uses the Oxsemi OXPCIe95x chipset) after updating their system from
> kernel 2.6.22.10 (which they patched because native support for the
> IQ Express didn't enter the kernel until 2.6.28) to kernel 2.6.36.
> 
> As I had never used any 2.6.36 kernel, myself, I explained that I
> had experienced no problem with the 2.6.35.6 kernel (as found in
> Fedora 14) at which point they installed kernel 2.6.35.8 and
> reported back that this had resolved the problem for them.
> 
> Following their report I then tested by installing the 2.6.37-rc4
> kernel (using 'make oldconfig', taking .config from the Fedora 14
> kernel that was working), and I was quickly able to determine that
> there were problems because simple communications with the modems
> were not working properly using 'minicom'.  (I also have now tested
> with 2.6.37-rc5 with the same result.)  Characters appear to be
> getting lost/dropped in the communication... for example, I *expect*
> the following on the minicom terminal screen when I start it up as
> it initializes the modem:
> 
> -------------------
> AT S7=45 S0=0 L1 V1 X4 &c1 E1 Q0
> OK
> 
> -------------------
> 
> The blinking cursor will be on the line following the OK.  This is
> what happens when using kernel 2.6.35.  However, when I use
> 2.6.37-rc5 this is what I see:
> 
> -------------------
> AT S7=45 S0=0 L1
> -------------------
> 
> Sometimes there is a character or two more on the screen but there
> will be no OK and the cursor will be blinking at the end of the line
> of commands... which leads me to believe that the modem did not see
> the CR+LF from the application.  If I simply press enter on the
> terminal, then I'll see the OK as expected.  So it seems to me that
> only the first bunch of characters are making it through and that
> the rest are getting dropped for some reason.
> 
> setserial tells me the following about the port:
> 
> # setserial -G /dev/ttyS4
> /dev/ttyS4 uart 16950/954 port 0x0000 irq 18 baud_base 4000000
> spd_normal skip_test
> 
> I think I can say with confidence that the problem started with 2.6.36.
> 
> What can I do to help solve the problem?

What type of device is this?  A pci card or something else?  What driver
controls it?

Also, the best thing to do would be if you could run 'git bisect' to
narrow the problem down to the specific patch that caused the problem.
Any chance you could do that?

thanks,

greg k-h