On 16-07-19, 11:24, Peter Ujfalusi wrote:
> When a DMA client driver does not set the DMA_PREP_INTERRUPT because it
> does not want to use interrupts for DMA completion or because it can not
> rely on DMA interrupts due to executing the memcpy when interrupts are
> disabled it will poll the status of the transfer.
>
> If the interrupts are enabled then the cookie will be set completed in the
> interrupt handler so only check in HW completion when the polling is really
> needed.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> ---
> drivers/dma/ti/omap-dma.c | 44 +++++++++++++++++++++++++--------------
> 1 file changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/dma/ti/omap-dma.c b/drivers/dma/ti/omap-dma.c
> index 029c0bd550d5..966d8f0323b5 100644
> --- a/drivers/dma/ti/omap-dma.c
> +++ b/drivers/dma/ti/omap-dma.c
> @@ -91,6 +91,7 @@ struct omap_desc {
> bool using_ll;
> enum dma_transfer_direction dir;
> dma_addr_t dev_addr;
> + bool polled;
>
> int32_t fi; /* for OMAP_DMA_SYNC_PACKET / double indexing */
> int16_t ei; /* for double indexing */
> @@ -815,26 +816,20 @@ static enum dma_status omap_dma_tx_status(struct dma_chan *chan,
> struct virt_dma_desc *vd;
> enum dma_status ret;
> unsigned long flags;
> + struct omap_desc *d = NULL;
>
> ret = dma_cookie_status(chan, cookie, txstate);
> -
> - if (!c->paused && c->running) {
> - uint32_t ccr = omap_dma_chan_read(c, CCR);
> - /*
> - * The channel is no longer active, set the return value
> - * accordingly
> - */
> - if (!(ccr & CCR_ENABLE))
> - ret = DMA_COMPLETE;
> - }
> -
> - if (ret == DMA_COMPLETE || !txstate)
> + if (ret == DMA_COMPLETE)
why do you want to continue for txstate being null?
Also it would lead to NULL ptr deref for txstate
> return ret;
>
> spin_lock_irqsave(&c->vc.lock, flags);
> + if (c->desc && c->desc->vd.tx.cookie == cookie)
> + d = c->desc;
> +
> + if (!txstate)
> + goto out;
>
> - if (c->desc && c->desc->vd.tx.cookie == cookie) {
> - struct omap_desc *d = c->desc;
> + if (d) {
> dma_addr_t pos;
>
> if (d->dir == DMA_MEM_TO_DEV)
> @@ -851,8 +846,22 @@ static enum dma_status omap_dma_tx_status(struct dma_chan *chan,
> txstate->residue = 0;
> }
>
> - if (ret == DMA_IN_PROGRESS && c->paused)
> +out:
> + if (ret == DMA_IN_PROGRESS && c->paused) {
> ret = DMA_PAUSED;
> + } else if (d && d->polled && c->running) {
> + uint32_t ccr = omap_dma_chan_read(c, CCR);
> + /*
> + * The channel is no longer active, set the return value
> + * accordingly and mark it as completed
> + */
> + if (!(ccr & CCR_ENABLE)) {
> + struct omap_desc *d = c->desc;
> + ret = DMA_COMPLETE;
> + omap_dma_start_desc(c);
> + vchan_cookie_complete(&d->vd);
> + }
> + }
>
> spin_unlock_irqrestore(&c->vc.lock, flags);
>
> @@ -1180,7 +1189,10 @@ static struct dma_async_tx_descriptor *omap_dma_prep_dma_memcpy(
> d->ccr = c->ccr;
> d->ccr |= CCR_DST_AMODE_POSTINC | CCR_SRC_AMODE_POSTINC;
>
> - d->cicr = CICR_DROP_IE | CICR_FRAME_IE;
> + if (tx_flags & DMA_PREP_INTERRUPT)
> + d->cicr |= CICR_FRAME_IE;
> + else
> + d->polled = true;
>
> d->csdp = data_type;
>
> --
> Peter
>
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
~Vinod
