On 01/22/2016 08:28 AM, John Ogness wrote: > If DMA is active during a shutdown, a delayed restore of the > registers may be pending. The restore must be performed after > the DMA is stopped, otherwise the delayed restore remains > pending and will fire upon the first DMA TX complete of a > totally different serial session. > > Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx> > --- > This patch was originally posted and discussed here: > http://lkml.kernel.org/r/87egjp2r4a.fsf@xxxxxxxxxxxxx > > The patch was not accepted because Peter expressed dissatisfaction with > the entire deferred implementation. (This patch fixes a bug in that > implementation.) However, no alternative solution was determined and the > bug continues to exist. Yeah, I made that comment a while ago and still no one's fixed that. What gives? Regards, Peter Hurley > Although we can certainly continue to debate about an alternate solution > to the deferred implementation, I think it makes sense to at least fix > the existing bug until an alternative exists. > > The bug can be easily produced with a `kill -9` on a process transmitting > on the serial port. > > patch against next-20160122 > > drivers/tty/serial/8250/8250_omap.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c > index a2c0734..0ffec67 100644 > --- a/drivers/tty/serial/8250/8250_omap.c > +++ b/drivers/tty/serial/8250/8250_omap.c > @@ -664,9 +664,15 @@ static void omap_8250_shutdown(struct uart_port *port) > up->ier = 0; > serial_out(up, UART_IER, 0); > > - if (up->dma) > + if (up->dma) { > serial8250_release_dma(up); > > + if (priv->delayed_restore) { > + priv->delayed_restore = 0; > + omap8250_restore_regs(up); > + } > + } > + > /* > * Disable break condition and FIFOs > */ > -- 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
