Date: Sun, 5 May 2013 12:59:17 +0100 From: =?ISO-8859-1?Q?Miguel_Barbosa_Gon=E7alves?= <m@mbg.pt> To: freebsd-questions@freebsd.org Subject: Disable FIFO on UART Message-ID: <CAEdntmtta6LQ3U62sod8vGggTT5f1mqoWE0cf0wma=MCs-uvNA@mail.gmail.com>
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Hi! Back in FreeBSD 7 there was a flag to disable the FIFO on the sio device driver. From http://www.freebsd.org/cgi/man.cgi?query=sio&apropos=0&sektion=0&manpath=FreeBSD+7.4-stable&arch=default&format=html: Meaning of flags: 0x00001 shared IRQs 0x00002 disable FIFO 0x00004 no AST/4 compatible IRQ control register 0x00008 recover sooner from lost output interrupts 0x00010 device is potential system console 0x00020 device is forced to become system console 0x00040 device is reserved for low-level IO (e.g. for remote kernel debugging) 0x00080 use this port for remote kernel debugging 0x0??00 minor number of master port 0x10000 PPS timestamping on CTS instead of DCD 0x20000 device is assumed to use a 16650A-type (extended FIFO) chip Now with FreeBSD 8 which uses the UART device driver there's no option for that. I am looking to reduce the jitter I am getting on the serial port when connecting a GPS to the server. Can anyone help? Regards, Miguel
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