Messages in this thread | | | Date | Thu, 26 Mar 2009 08:42:20 +0100 | From | Paul Rolland <> | Subject | Linux 2.6.x - Serial port signalling not maintained when closing device |
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Hello,
I'm using small devices that are connected on the serial port, and powered using RTS and DTR. When using kernel 2.4.x (at least 2.4.31), I could easily control the powering of the device using : stty -F /dev/ttyS0 ospeed 9600 (this would put RTS and DTR to 1 / power) and stty -F /dev/ttyS0 ospeed 0 (this would turn it off).
I've recently updated one of the machine to a new 2.6.29 kernel, and this is not working anymore. As far as I can see, I need to have an application that keeps /dev/ttyS0 open for this to work. As soon as no application is using the port, everything goes down again.
This is a significant change between 2.4.x and 2.6.x. Is there a way to change 2.6.x behavior to go back to the 2.4.x ? When was this change introduce ?
This serial port controler is a 16550A, the machine is an x86 platform, so nothing unusual.
Best regards, Paul
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