On Thursday 11 February 2010 11:58:47 am Brian Murphy wrote: > Hi Folks, > We have been working with L137 and there is an issue where the serial > driver handles > the UART in a very bad way. This may be the same issue as described > in the other > two mails on this thread. > The issue is that the serial driver 8250.c expects the uart to > generate a fifo empty interrupt > if the FIFO is empty and interrupts are enabled. The UART in the L137 > only generates a FIFO > empty interrupt the first time. The serial driver handles this > situation by starting a timer which > times out after 200ms when interrupts are enabled and only then begins > to transmit. > I have rewritten the interrupt handling so the driver maintains a flag > which tells whether the UART > is currently transmitting or not. If not then we begin filling the TX > fifo immediately (we do not > wait for an interrupt which never comes). This fixes the transmit > latency issue for us. > > I have attached the patch. It is against the linux-davinci git at > kernel.org as of friday last week. > > I have sent the patch to the linux-serial list with no response. > > Could you who have problems with serial performance test the patch? I > can try to send it > again to linux-serial if I get good feedback from you. >
This patch solves the problem for DM6446. Thanks for sharing your work. Best Regards, Caglar > /Brian > _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
