diff mbox series

[v2,6/6] dmaengine: sun6i: keep cyclic state with the prepared descriptor

Message ID 20261023-submit-sun6i-dma-lifetime-next-v1-v2-6-c9e07cc44bf8@gmail.com (mailing list archive)
State New
Headers
Series dmaengine: sun6i: fix interrupt routing and channel lifetime |

Commit Message

James Hilliard Oct. 23, 2026, 6:42 p.m. UTC 
Preparing a cyclic transfer sets vchan->cyclic before the descriptor is
submitted. A finite transfer on that channel can then select package
interrupts and take the cyclic callback path instead of completing its
cookie. Merely preparing an unrelated future transfer must not change
the active transfer or the meaning of queued descriptors.

Store the flag in sun6i_desc and consult the active descriptor when
selecting interrupts, completing a transfer and terminating it. Finite
descriptors retain their zero-initialized flag. This also makes callback
retirement depend on the descriptor whose lifetime is being ended.

The shared state was identified during the H616 cyclic UART RX review.

Fixes: a90e173f3faf ("dmaengine: sun6i: Add cyclic capability")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/dma/sun6i-dma.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index c244ef572492..c9a72cfe3f44 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -191,6 +191,7 @@  struct sun6i_desc {
 	struct virt_dma_desc	vd;
 	dma_addr_t		p_lli;
 	struct sun6i_dma_lli	*v_lli;
+	bool			cyclic;
 };
 
 struct sun6i_pchan {
@@ -207,7 +208,6 @@  struct sun6i_vchan {
 	struct sun6i_pchan	*phy;
 	u8			port;
 	u8			irq_type;
-	bool			cyclic;
 	bool			paused;
 };
 
@@ -504,7 +504,7 @@  static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
 			     (DMA_IRQ_HALF | DMA_IRQ_PKG | DMA_IRQ_QUEUE) <<
 			     (irq_offset * DMA_IRQ_CHAN_WIDTH));
 
-	vchan->irq_type = vchan->cyclic ? DMA_IRQ_PKG : DMA_IRQ_QUEUE;
+	vchan->irq_type = pchan->desc->cyclic ? DMA_IRQ_PKG : DMA_IRQ_QUEUE;
 
 	irq_val = sun6i_read_irq_en(sdev, irq_reg);
 	irq_val &= ~((DMA_IRQ_HALF | DMA_IRQ_PKG | DMA_IRQ_QUEUE) <<
@@ -607,7 +607,7 @@  static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 			desc = pchan->desc;
 			if (vchan && desc && (status & vchan->irq_type)) {
 				spin_lock(&vchan->vc.lock);
-				if (vchan->cyclic) {
+				if (desc->cyclic) {
 					vchan_cyclic_callback(&desc->vd);
 				} else {
 					/* Completion transfers ownership to virt-dma. */
@@ -908,7 +908,7 @@  static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_cyclic(
 
 	prev->p_lli_next = txd->p_lli;		/* cyclic list */
 
-	vchan->cyclic = true;
+	txd->cyclic = true;
 
 	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
 
@@ -997,13 +997,12 @@  static int sun6i_dma_terminate_all(struct dma_chan *chan)
 		struct virt_dma_desc *vd = &pchan->desc->vd;
 
 		/* A cyclic callback may still hold this descriptor outside vc.lock. */
-		if (vchan->cyclic)
+		if (pchan->desc->cyclic)
 			vchan_terminate_vdesc(vd);
 		else
 			list_add_tail(&vd->node, &head);
 	}
 
-	vchan->cyclic = false;
 	vchan->paused = false;
 	/* Leave terminated cyclic descriptors for the sleepable synchronize. */
 	list_splice_tail_init(&vchan->vc.desc_allocated, &head);