From mboxrd@z Thu Jan 1 00:00:00 1970 From: zentrale.at.work@gmail.com (Josef Holzmayr) Date: Wed, 11 Nov 2009 14:59:23 +0100 Subject: atmel_serial losing characters under libmodbus In-Reply-To: References: <4AFAB1BE.4040008@gmail.com> Message-ID: <4AFAC33B.2090406@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org christian pellegrin wrote: > On Wed, Nov 11, 2009 at 1:44 PM, Josef Holzmayr > wrote: >> When using libmodbus on an atmel_serial line, it seems to lose about 1 char >> in 50 that it's supposed to receive. This is independet of the baud rate, it >> happens everywhere from 2400 to 19200. Full code excerpt from the lib is >> below, but basically reading is just an select/read pair. Are there some >> known issues with that particular tty device? >> > > Hi, the only serial port on AT91 that gives me troubles is the DBGU > port which shares the interrupt with the timer tick. You see a lot of > serial overruns there if you have the kernel compiled with HZ=1000 on > that port (usually ttyS0). > Thanks for the hint, but iv'e got this problem reproducable on ttyS2 and ttyS4. CONFIG_HZ is 128, and whats really interesting: if you use an usb-to-serial converter instead, everything works like a charm. -- Josef"ZaP" Holzmayr "Never underestimate the bandwidth of a freight train full of DAT tapes. Just latency might be an issue"