Hello,
On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote:
> From: Nandor Han <nandor.han@xxxxxx>
>
> 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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