> -----Original Message----- > From: Grant Edwards > Sent: Thursday, July 10, 2008 4:48 PM ... > > On 2008-07-10, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote: ... > > Do we really benefit from having this in kernel ? > > People who do industrial communications sure would. I maintain > a couple serial drivers that support half-duplex mode exactly > as described by the OP, and we have to control that feature via > non-standard hacks. ... I fully agree with Grant Edwards. I, as well, have been myself maintaining two serial drivers that support half-duplex mode exactly as described, and I have to control that feature via non-standard hacks !!! I have been porting them over and over again with each Linux version and subversion, since Linux 2.2, and there IS a demand for it. About the benefit to have this in the kernel: well, we would be enabled to implement it for any UART, not just the 16550 series ! Now, about Linux RT and response times: The TXD-to-RTS delay must be as short as possible. To do this, several UARTS i.e. (Ox950) have a special mode. How could you do this in a user land program for any baud rate ? I speak about baud rates up to 2 Mbps, they are in use nowadays on RS2422/RS485 lines. Really, I would like AT LEAST some commonly defined way to activate this behaviour. Russell King once suggested to create a line discipline to handle the RTS, but even like this we need a way (an ioctl) to activate the behaviour in the UART driver, to make it independent from the specific UART. JP Tosoni Acksys -- 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
