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[v3,5/9] dmaengine: sun6i: detach completed descriptors before invoking callbacks

Message ID 20261023-submit-sun6i-dma-lifetime-next-v1-v3-5-ef1acb0be768@gmail.com (mailing list archive)
State New
Headers
Series dmaengine: sun6i: fix interrupt routing and channel lifetime |

Commit Message

James Hilliard Oct. 23, 2026, 11:38 p.m. UTC 
Finite completion publishes a descriptor to virt-dma but leaves pchan->desc
pointing to it until the allocator runs. The virtual-channel tasklet may
free that descriptor first. A residue query for another incomplete cookie
can still pass the retired descriptor to sun6i_get_chan_size().

Clear the active descriptor pointer before publishing completion. An
assigned physical channel without a descriptor is ready for the allocator
to start its next transfer or release it. Use that state in place of the
completed-descriptor pointer, so residue queries and termination only
consult descriptors still owned by the physical channel.

Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/dma/sun6i-dma.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)
diff mbox series

Patch

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index d3a63c866645..900bb629ba3b 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -198,7 +198,6 @@  struct sun6i_pchan {
 	void __iomem		*base;
 	struct sun6i_vchan	*vchan;
 	struct sun6i_desc	*desc;
-	struct sun6i_desc	*done;
 };
 
 struct sun6i_vchan {
@@ -490,16 +489,12 @@  static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
 	if (!pchan)
 		return -EAGAIN;
 
-	if (!desc) {
-		pchan->desc = NULL;
-		pchan->done = NULL;
+	if (!desc)
 		return -EAGAIN;
-	}
 
 	list_del(&desc->node);
 
 	pchan->desc = to_sun6i_desc(&desc->tx);
-	pchan->done = NULL;
 
 	sun6i_dma_dump_lli(vchan, pchan->desc->v_lli, pchan->desc->p_lli);
 
@@ -536,7 +531,7 @@  static void sun6i_dma_tasklet(struct tasklet_struct *t)
 
 		pchan = vchan->phy;
 
-		if (pchan && pchan->done) {
+		if (pchan && !pchan->desc) {
 			if (sun6i_dma_start_desc(vchan)) {
 				/*
 				 * No current txd associated with this channel
@@ -582,6 +577,7 @@  static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 	u32 channels_per_reg = sdev->cfg->num_channels_per_reg;
 	struct sun6i_vchan *vchan;
 	struct sun6i_pchan *pchan;
+	struct sun6i_desc *desc;
 	unsigned long flags;
 	int i, j, ret = IRQ_NONE;
 	u32 status;
@@ -601,13 +597,15 @@  static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 		     i * channels_per_reg + j < sdev->num_pchans; j++) {
 			pchan = sdev->pchans + i * channels_per_reg + j;
 			vchan = pchan->vchan;
-			if (vchan && (status & vchan->irq_type)) {
+			desc = pchan->desc;
+			if (vchan && desc && (status & vchan->irq_type)) {
 				spin_lock(&vchan->vc.lock);
 				if (vchan->cyclic) {
-					vchan_cyclic_callback(&pchan->desc->vd);
+					vchan_cyclic_callback(&desc->vd);
 				} else {
-					vchan_cookie_complete(&pchan->desc->vd);
-					pchan->done = pchan->desc;
+					/* Completion transfers ownership to virt-dma. */
+					pchan->desc = NULL;
+					vchan_cookie_complete(&desc->vd);
 				}
 				spin_unlock(&vchan->vc.lock);
 			}
@@ -983,7 +981,7 @@  static int sun6i_dma_terminate_all(struct dma_chan *chan)
 	pchan = vchan->phy;
 	list_del_init(&vchan->node);
 
-	if (pchan && pchan->desc && pchan->desc != pchan->done) {
+	if (pchan && pchan->desc) {
 		struct virt_dma_desc *vd = &pchan->desc->vd;
 
 		vchan_terminate_vdesc(vd);
@@ -999,7 +997,6 @@  static int sun6i_dma_terminate_all(struct dma_chan *chan)
 		vchan->phy = NULL;
 		pchan->vchan = NULL;
 		pchan->desc = NULL;
-		pchan->done = NULL;
 	}
 
 	spin_unlock(&vchan->vc.lock);