Hello,
Le 03/07/2017 à 08:48, Uwe Kleine-König a écrit : > Hello, > > On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote: >> From: Nandor Han <[email protected]> >> >> Avoid the situation when `dma_is_rxing` could incorrectly signal that >> DMA RX channel is receiving data in case DMA preparation or sg mapping >> fails. > Just from reading the commit log and the patch I didn't understand the > problem that is supposed to be fixed here. After looking at it for some > I understood. I don't suggest a new commit log here as it has to look > different if you pick up my comment below. > >> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c >> index 5437b34..1d35293 100644 >> --- a/drivers/tty/serial/imx.c >> +++ b/drivers/tty/serial/imx.c >> @@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id) >> return IRQ_HANDLED; >> } >> >> -static void imx_disable_rx_int(struct imx_port *sport) >> +static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing) >> { >> unsigned long temp; >> >> - sport->dma_is_rxing = 1; >> + sport->dma_is_rxing = is_rxing; >> >> /* disable the receiver ready and aging timer interrupts */ >> temp = readl(sport->port.membase + UCR1); >> @@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport) >> temp = readl(sport->port.membase + USR2); >> if ((temp & USR2_RDR) && !sport->dma_is_rxing) { >> >> - imx_disable_rx_int(sport); >> + imx_disable_rx_int(sport, false); >> >> /* tell the DMA to receive the data. */ >> start_rx_dma(sport); >> @@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport) >> desc->callback_param = sport; >> >> dev_dbg(dev, "RX: prepare for the DMA.\n"); >> + sport->dma_is_rxing = 1; >> sport->rx_cookie = dmaengine_submit(desc); >> dma_async_issue_pending(chan); >> return 0; >> @@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port) >> spin_unlock(&tty->files_lock); >> >> if (readcnt > 0) { >> - imx_disable_rx_int(sport); >> + imx_disable_rx_int(sport, true); > I wonder if it would be saner to not assign to dma_is_rxing in > imx_disable_rx_int() at all but do this only in start_rx_dma() and > imx_dma_rxint(). It was "mostly" done, in 4.11 in fact. dma_is_rxing was set to 0 from imx_dma_rxint() and was not set at all from start_rx_dma(), resulting to the same issue. We could move assignment of dma_is_rxing out of imx_disable_rx_int() and set it to one from start_rx_dma() only. What do you think ? Best Regards, Romain > > Best regards > Uwe >
