On Fri, Feb 12, 2016 at 05:14:58AM +0000, Michal Meloun wrote: > Author: mmel > Date: Fri Feb 12 05:14:58 2016 > New Revision: 295557 > URL: https://svnweb.freebsd.org/changeset/base/295557 > > Log: > UART: Fix spurious interrupts generated by ns8250 and lpc drivers: > - don't enable transmitter empty interrupt before filling TX FIFO.
Are you sure this doesn't create a race that leads to lost TX ready interrupts? For a single character, the TX FIFO very well may be empty again at the point in time IER_ETXRDY is enabled now. With the varying behavior of 8250/16x50 chips - some of which is documented in sio(4) - I'd expect there are many that no longer generate a TX ready at all with this change in place. In this case, receiving spurious interrupts (which ones? IIR_NOPEND? IIR_TXRDY?) with some devices appears to be the lesser evil. Marius _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
