2.6.25 upgraded to 2.6.36: serial app stops working

2.6.25 upgraded to 2.6.36: serial app stops working

[folkert]

Hi,

I upgraded my linux system to 2.6.36. Now suddenly my serial driver for
my MSF receiver stopped working. Two things I noticed: I need to open
the serial device (/dev/ttyS0, a regular uart, see below) with O_NDELAY
for open() to return at all. Then something funny happens: I read bytes
from the device (at 50bps) which runs fine for a while but then suddenly
I get a burst of '0x00' bytes - precisely at the point at which the MSF
radio device sends a timecode! So I think the device fiddles with one of
the pins of the serial port confusing the linux serial driver. This
worked fine upto and including 2.6.25 (maybe later too) but with 2.6.36
this fails.
Anyone an idea what might go wrong here? And how to fix it?
The sourcecode of my driver can be found here:
http://vanheusden.com/lpc-ntpd/lindy_precision_clock.php

[    0.826110] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    2.596509] 0000:04:06.0: ttyS0 at I/O 0xbf00 (irq = 20) is a 16550A
[    2.617685] 0000:04:06.0: ttyS1 at I/O 0xbe00 (irq = 20) is a 16550A

weerstationserver:/usr/local/src/lpc-ntpd-1.0.1.hacked# setserial -a -g /dev/ttyS0
/dev/ttyS0, Line 0, UART: 16550A, Port: 0xbf00, IRQ: 20
        Baud_base: 115200, close_delay: 50, divisor: 0
        closing_wait: 3000
        Flags: spd_normal skip_test


Folkert van Heusden

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Re: 2.6.25 upgraded to 2.6.36: serial app stops working

[Greg KH]

On Tue, Nov 30, 2010 at 05:27:55PM +0100, folkert wrote:
> Hi,
> 
> I upgraded my linux system to 2.6.36. Now suddenly my serial driver for
> my MSF receiver stopped working. Two things I noticed: I need to open
> the serial device (/dev/ttyS0, a regular uart, see below) with O_NDELAY
> for open() to return at all. Then something funny happens: I read bytes
> from the device (at 50bps) which runs fine for a while but then suddenly
> I get a burst of '0x00' bytes - precisely at the point at which the MSF
> radio device sends a timecode! So I think the device fiddles with one of
> the pins of the serial port confusing the linux serial driver. This
> worked fine upto and including 2.6.25 (maybe later too) but with 2.6.36
> this fails.
> Anyone an idea what might go wrong here? And how to fix it?

Any chance you could use 'git bisect' on the kernel tree to see what
caused the change?  Moving from .25 to .36 is a huge jump, many many
years of development and loads of things have changed so we need some
help to narrow the problem down.

thanks,

greg k-h

Re: 2.6.25 upgraded to 2.6.36: serial app stops working

[folkert]

> > I upgraded my linux system to 2.6.36. Now suddenly my serial driver for
> > my MSF receiver stopped working. Two things I noticed: I need to open
> > the serial device (/dev/ttyS0, a regular uart, see below) with O_NDELAY
> > for open() to return at all. Then something funny happens: I read bytes
> > from the device (at 50bps) which runs fine for a while but then suddenly
> > I get a burst of '0x00' bytes - precisely at the point at which the MSF
> > radio device sends a timecode! So I think the device fiddles with one of
> > the pins of the serial port confusing the linux serial driver. This
> > worked fine upto and including 2.6.25 (maybe later too) but with 2.6.36
> > this fails.
> > Anyone an idea what might go wrong here? And how to fix it?
> 
> Any chance you could use 'git bisect' on the kernel tree to see what
> caused the change?  Moving from .25 to .36 is a huge jump, many many
> years of development and loads of things have changed so we need some
> help to narrow the problem down.

Hmmm, I might have missed this message :-)
Anyway a few months ago I retried it and had same problem. BUT: the
other receiver I have, has a serial-to-usb converter in it. So it is an
USB device but maybe a special one? Anyway: it has exact the same
problem. It is possible that maybe they're just broken both.
As you may deduct from my replying-delay, it has no great priority for
me.


Folkert van Heusden

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Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com

Re: 2.6.25 upgraded to 2.6.36: serial app stops working

[folkert]

> > I upgraded my linux system to 2.6.36. Now suddenly my serial driver
> > for
> > my MSF receiver stopped working. Two things I noticed: I need to open
> > the serial device (/dev/ttyS0, a regular uart, see below) with
> > O_NDELAY
> > for open() to return at all. Then something funny happens: I read
> > bytes
> > from the device (at 50bps) which runs fine for a while but then
> > suddenly
> > I get a burst of '0x00' bytes - precisely at the point at which the
> > MSF
> > radio device sends a timecode! So I think the device fiddles with one
> > of
> > the pins of the serial port confusing the linux serial driver. This
> > worked fine upto and including 2.6.25 (maybe later too) but with
> > 2.6.36
> > this fails.
> > Anyone an idea what might go wrong here? And how to fix it?

> Any chance you could use 'git bisect' on the kernel tree to see what
> caused the change?  Moving from .25 to .36 is a huge jump, many many
> years of development and loads of things have changed so we need some
> help to narrow the problem down.

Am looking for a way to do that: the original system has ext4
filesystems so .25 is a bit tricky. An other system (via Csomething)
crashes with .25.


Folkert van Heusden

-- 
Nagios user? Check out CoffeeSaint - the versatile Nagios status
viewer! http://www.vanheusden.com/java/CoffeeSaint/
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