Hi Greg, Op 19 april 2012 02:14 heeft Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> het volgende geschreven: > On Tue, Apr 17, 2012 at 04:38:30PM +0200, Ivo Sieben wrote: >> Hello, >> >> We are currently using the TTY framework for serial communication. >> >> We are wondering if it is possible to give the TTY device in more >> deterministic behavior (as in "less locks & no sleeping") > > What specifically are you looking for? > We run an application with a real-time thread, running on a high priority. This thread does serial communication, using non blocking read/write file I/O on a tty device, with small amounts of data (= 24 bytes). This application runs on a AT2AM9261 processor, 200 MHz The maximum execution time of both the read & write go up to 200 us >> So in case of non blocking read/write behavior: >> - We want directly write data to the serial_core transmit buffer and >> return immediately. > > What is "immediately"? > We use non blocking read & write functions We would like the read/write functions to always execute less than 100us >> - Incoming data should be buffered, on a read data is read directly >> from that buffer and when no data available return immediately > > That doesn't happen today? > > What type of latencies are you seeing today that is bothering you? What > hardware are you expecting to work in this manner? What exact UART are > you using? What happens when the UART buffers data? > > thanks, > > greg k-h We use a self written serial_core device uart driver that implements a driver for a UART peripheral in a FPGA on our target board.. -- 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
