[PATCH v2 13/19] dmaengine: dw-edma: Make the LL ring reset a full channel resync

[Koichiro Den]

Reset currently clears the ring but leaves issued descriptors unchanged.
A descriptor with published entries is then stranded because LL progress
can no longer account for those entries.

Keep descriptors with no outstanding published entries so their
unpublished work can use the fresh ring. Abort descriptors with
outstanding entries because their consumption is unknown and replay is
unsafe.

Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v2:
  - New patch.

 drivers/dma/dw-edma/dw-edma-core.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 3fc929a6bcf5..963abecdc59e 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -100,8 +100,27 @@ static void dw_hdma_set_callback_result(struct virt_dma_desc *vd,
 
 static void dw_edma_core_reset_ll(struct dw_edma_chan *chan)
 {
+	struct virt_dma_desc *vd, *tmp;
 	u32 i;
 
+	/*
+	 * Software cannot tell which published entries completed before the
+	 * reset. Replaying one could duplicate a transfer after its target
+	 * changed ownership, while keeping descriptors with uncertain entries
+	 * would block later in-order completions. Abort descriptors with published
+	 * entries; untouched descriptors remain available for republishing.
+	 */
+	list_for_each_entry_safe(vd, tmp, &chan->vc.desc_issued, node) {
+		struct dw_edma_desc *desc = vd2dw_edma_desc(vd);
+
+		if (desc->start_burst == desc->done_burst)
+			continue;
+
+		dw_hdma_set_callback_result(vd, DMA_TRANS_ABORTED);
+		list_del(&vd->node);
+		vchan_cookie_complete(vd);
+	}
+
 	chan->ll_head = 0;
 	chan->ll_done = 0;
 	dw_edma_ll_irq_idx_discard(chan);
-- 
2.51.0