Messages in this thread Patch in this message | | | Date | Mon, 3 Jul 2017 08:48:40 +0200 | From | Uwe Kleine-König <> | Subject | Re: [PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts |
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Hello,
On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote: > From: Nandor Han <nandor.han@ge.com> > > 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().
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
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