On Fri, May 24, 2019 at 06:47:33AM +0000, Rautkoski Kimmo EXT wrote: > Interrupt handler checked THRE bit (transmitter holding register > empty) in LSR to detect if TX fifo is empty. > In case when there is only receive interrupts the TX handling > got called because THRE bit in LSR is set when there is no > transmission (FIFO empty). TX handling caused TX stop, which in > RS-485 half-duplex mode actually resets receiver FIFO. This is not > desired during reception because of possible data loss. > > The fix is to check if THRI is set in IER in addition of the TX > fifo status. THRI in IER is set when TX is started and cleared > when TX is stopped. > This ensures that TX handling is only called when there is really > transmission on going and an interrupt for THRE and not when there > are only RX interrupts. > > Signed-off-by: Kimmo Rautkoski <ext-kimmo.rautkoski@xxxxxxxxxxx> > --- > drivers/tty/serial/8250/8250_port.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > What changed from all of the previous versions of this patch? That needs to go below the --- line. Please fix up and resend a v4. thanks, greg k-h
