Dear Hector Palacios,
> The ISR was handling CTS flag and RX/TX processing.
> Occasionally interrupts were coming in the middle of the ISR and
> led to blocking transmission (with hw flow) or loss of data.
> This patch moves this processing to a tasklet that the ISR schedules.
>
> Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
> ---
> drivers/tty/serial/mxs-auart.c | 61
> +++++++++++++++++++++++++++--------------- 1 file changed, 39
> insertions(+), 22 deletions(-)
>
> diff --git a/drivers/tty/serial/mxs-auart.c
> b/drivers/tty/serial/mxs-auart.c index e5540c89dd48..7021269c70b2 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -148,6 +148,10 @@ struct mxs_auart_port {
> struct clk *clk;
> struct device *dev;
>
> + struct tasklet_struct tasklet;
> + unsigned int irq_status;
> + unsigned int status;
> +
> /* for DMA */
> struct scatterlist tx_sgl;
> struct dma_chan *tx_dma_chan;
> @@ -680,38 +684,48 @@ static void mxs_auart_settermios(struct uart_port *u,
> }
> }
>
> +/*
> + * tasklet handling tty stuff outside the interrupt handler.
> + */
> +static void mxs_auart_tasklet_func(unsigned long data)
> +{
> + struct uart_port *port = (struct uart_port *)data;
> + struct mxs_auart_port *s = to_auart_port(port);
> +
> + /* Handle status irq */
> + if (s->irq_status & AUART_INTR_CTSMIS) {
> + uart_handle_cts_change(&s->port, s->status & AUART_STAT_CTS);
> + writel(AUART_INTR_CTSMIS,
> + s->port.membase + AUART_INTR_CLR);
> + }
> + /* Handle receive irq */
> + if (s->irq_status & (AUART_INTR_RTIS | AUART_INTR_RXIS)) {
> + if (!auart_dma_enabled(s))
> + mxs_auart_rx_chars(s);
> + }
> + /* Handle transmit irq */
> + if (s->irq_status & AUART_INTR_TXIS)
> + mxs_auart_tx_chars(s);
> +}
> +
> static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
> {
> - u32 istat;
> struct mxs_auart_port *s = context;
> - u32 stat = readl(s->port.membase + AUART_STAT);
>
> - istat = readl(s->port.membase + AUART_INTR);
> + s->status = readl(s->port.membase + AUART_STAT);
> + s->irq_status = readl(s->port.membase + AUART_INTR);
Aren't you up for a nice race condition here if you get interrupt while checking
the s->irq_status bits in the tasklet ?
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