Hi Lukas,
> Lukas Wunner <lukas@xxxxxxxxx> hat am 22. Dezember 2018 um 08:28 geschrieben:
>
>
> ...
> drivers/dma/bcm2835-dma.c | 33 +++------------------------------
> 1 file changed, 3 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index e94f41c56975..17bc7304db3a 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -419,25 +419,11 @@ static int bcm2835_dma_abort(void __iomem *chan_base)
> writel(0, chan_base + BCM2835_DMA_CS);
>
> /* Wait for any current AXI transfer to complete */
> - while ((cs & BCM2835_DMA_ISPAUSED) && --timeout) {
> + while ((readl(chan_base + BCM2835_DMA_CS) &
> + BCM2835_DMA_WAITING_FOR_WRITES) && --timeout)
> cpu_relax();
> - cs = readl(chan_base + BCM2835_DMA_CS);
> - }
> -
> - /* We'll un-pause when we set of our next DMA */
> - if (!timeout)
> - return -ETIMEDOUT;
i'm only sceptical about silently ignoring the timeout case. I prefer to have a comment explaining why we proceed with BCM2835_DMA_RESET in this case and some kind of error / debug message like below.
> -
> - if (!(cs & BCM2835_DMA_ACTIVE))
> - return 0;
> -
> - /* Terminate the control block chain */
> - writel(0, chan_base + BCM2835_DMA_NEXTCB);
> -
> - /* Abort the whole DMA */
> - writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
> - chan_base + BCM2835_DMA_CS);
>
> + writel(BCM2835_DMA_RESET, chan_base + BCM2835_DMA_CS);
> return 0;
> }
>
> @@ -787,7 +773,6 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
> struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
> unsigned long flags;
> - int timeout = 10000;
> LIST_HEAD(head);
>
> spin_lock_irqsave(&c->vc.lock, flags);
> @@ -802,18 +787,6 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
> vchan_terminate_vdesc(&c->desc->vd);
> c->desc = NULL;
> bcm2835_dma_abort(c->chan_base);
> -
> - /* Wait for stopping */
> - while (--timeout) {
> - if (!(readl(c->chan_base + BCM2835_DMA_CS) &
> - BCM2835_DMA_ACTIVE))
> - break;
> -
> - cpu_relax();
> - }
> -
> - if (!timeout)
> - dev_err(d->ddev.dev, "DMA transfer could not be terminated\n");
> }
>
Stefan
