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dmaengine: dma-axi-dmac: Gracefully terminate SW cyclic transfers

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As of now, to terminate a cyclic transfer, one pretty much needs to use
brute force and terminate all transfers with .device_terminate_all().
With this change, when a cyclic transfer terminates (and generates an
EOT interrupt), look at any new pending transfer with the DMA_PREP_LOAD_EOT
flag set. If there is one, the current cyclic transfer is terminated and
the next one is enqueued. If the flag is not set, that transfer is ignored.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20260303-axi-dac-cyclic-support-v2-4-0db27b4be95a@analog.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Nuno Sá
2026-03-03 10:25:03 +00:00
committed by Vinod Koul
parent c60990ba1f
commit ca3bf200de
1 changed files with 33 additions and 1 deletions
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34
drivers/dma/dma-axi-dmac.c
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@@ -233,6 +233,11 @@ static struct axi_dmac_desc *axi_dmac_get_next_desc(struct axi_dmac *dmac,
struct virt_dma_desc *vdesc;
struct axi_dmac_desc *desc;
/*
* It means a SW cyclic transfer is in place so we should just return
* the same descriptor. SW cyclic transfer termination is handled
* in axi_dmac_transfer_done().
*/
if (chan->next_desc)
return chan->next_desc;
@@ -411,6 +416,32 @@ static void axi_dmac_compute_residue(struct axi_dmac_chan *chan,
}
}
static bool axi_dmac_handle_cyclic_eot(struct axi_dmac_chan *chan,
struct axi_dmac_desc *active)
{
struct device *dev = chan_to_axi_dmac(chan)->dma_dev.dev;
struct virt_dma_desc *vdesc;
/* wrap around */
active->num_completed = 0;
vdesc = vchan_next_desc(&chan->vchan);
if (!vdesc)
return false;
if (!(vdesc->tx.flags & DMA_PREP_LOAD_EOT)) {
dev_warn(dev, "Discarding non EOT transfer after cyclic\n");
list_del(&vdesc->node);
return false;
}
/* then let's end the cyclic transfer */
chan->next_desc = NULL;
list_del(&active->vdesc.node);
vchan_cookie_complete(&active->vdesc);
return true;
}
static bool axi_dmac_transfer_done(struct axi_dmac_chan *chan,
unsigned int completed_transfers)
{
@@ -458,7 +489,8 @@ static bool axi_dmac_transfer_done(struct axi_dmac_chan *chan,
if (active->num_completed == active->num_sgs ||
sg->partial_len) {
if (active->cyclic) {
active->num_completed = 0; /* wrap around */
/* keep start_next as is, if already true... */
start_next |= axi_dmac_handle_cyclic_eot(chan, active);
} else {
list_del(&active->vdesc.node);
vchan_cookie_complete(&active->vdesc);