Dear Ezequiel Garcia, On Wed, 27 Nov 2013 15:54:49 -0300, Ezequiel Garcia wrote: > > An external device may be keeping the UART busy and preventing LCR > > from being written. > > > > What device is attached to ttyS1? > > There's no device attached at ttyS1. I've just tested this in another > box and it seems the same error is obtained on each unused port: Are you sure about this? I suppose you're testing on the Armada XP GP board, and this board has a 4 ports FTDI chip, and according to the board schematics the four UARTs are all connected to the FTDI chip. So from the SoC perspective, ttyS1 is connected to something, as far as I can understand. Or maybe you also tested Armada XP DB ? Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html