On 04/07/2016 01:37 PM, Andy Shevchenko wrote:
> If we get an exeption interrupt. i.e. UART_IIR_RLSI, stop any ongoing RX DMA
> transfer otherwise it might generates more spurious interrupts and make port
> unavailable anymore.
Then how to know which rx byte the error is for if dma continues anyway?
What if there are multiple error bytes?
> As has been seen on Intel Broxton system:
This system shouldn't be setup for UART DMA imo.
> ...
> [ 168.526281] serial8250: too much work for irq5
> [ 168.535908] serial8250: too much work for irq5
> [ 173.449464] serial8250_interrupt: 4439 callbacks suppressed
> [ 173.455694] serial8250: too much work for irq5
> ...
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_dma.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
> index 9d80bb1..b134bec 100644
> --- a/drivers/tty/serial/8250/8250_dma.c
> +++ b/drivers/tty/serial/8250/8250_dma.c
> @@ -110,6 +110,16 @@ err:
> return ret;
> }
>
> +static void __dma_rx_stop(struct uart_8250_port *p, struct uart_8250_dma *dma)
> +{
> + if (!dma->rx_running)
> + return;
> +
> + dmaengine_pause(dma->rxchan);
> + __dma_rx_complete(p);
> + dmaengine_terminate_async(dma->rxchan);
> +}
> +
> int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
> {
> struct uart_8250_dma *dma = p->dma;
> @@ -118,17 +128,14 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
> switch (iir & 0x3f) {
> case UART_IIR_RLSI:
> /* 8250_core handles errors and break interrupts */
> + __dma_rx_stop(p, dma);
> return -EIO;
> case UART_IIR_RX_TIMEOUT:
> /*
> * If RCVR FIFO trigger level was not reached, complete the
> * transfer and let 8250_core copy the remaining data.
> */
> - if (dma->rx_running) {
> - dmaengine_pause(dma->rxchan);
> - __dma_rx_complete(p);
> - dmaengine_terminate_async(dma->rxchan);
> - }
> + __dma_rx_stop(p, dma);
> return -ETIMEDOUT;
> default:
> break;
>
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