[PATCH 1/2] net: ethernet: sun4i-emac: free dma desc

[PATCH 1/2] net: ethernet: sun4i-emac: free dma desc

[Conley Lee]

In the current implementation of the sun4i-emac driver,when using DMA to receive data packets,
the descriptor for the current DMA request is not released in the rx_done_callback.
This patch fixes this bug.

Signed-off-by: Conley Lee <conleylee@foxmail.com>
---
 drivers/net/ethernet/allwinner/sun4i-emac.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/allwinner/sun4i-emac.c b/drivers/net/ethernet/allwinner/sun4i-emac.c
index 2f516b950..2f990d0a5 100644
--- a/drivers/net/ethernet/allwinner/sun4i-emac.c
+++ b/drivers/net/ethernet/allwinner/sun4i-emac.c
@@ -237,6 +237,7 @@ emac_alloc_dma_req(struct emac_board_info *db,
 
 static void emac_free_dma_req(struct emac_dma_req *req)
 {
+	dmaengine_desc_free(req->desc);
 	kfree(req);
 }
 
-- 
2.25.1

Re: [PATCH 1/2] net: ethernet: sun4i-emac: free dma desc

[Jakub Kicinski]

On Sat, 30 Aug 2025 15:49:46 +0800 Conley Lee wrote:
> In the current implementation of the sun4i-emac driver,when using DMA to receive data packets,
> the descriptor for the current DMA request is not released in the rx_done_callback.

Please wrap the description at 74 columns.

> This patch fixes this bug.

Please use imperative mood, "Fix this." or even better rewrite the
whole commit msg to be imperative.

Since this is a fix please add a Fixes tag.

[PATCH] net: ethernet: sun4i-emac: free dma descriptor

[Conley Lee]

In the current implementation of the sun4i-emac driver, when using DMA to
receive data packets, the descriptor for the current DMA request is not
released in the rx_done_callback.

Fix this by properly releasing the descriptor.

Fixes: 47869e82c8b8 ("sun4i-emac.c: add dma support")
Signed-off-by: Conley Lee <conleylee@foxmail.com>
---
 drivers/net/ethernet/allwinner/sun4i-emac.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/allwinner/sun4i-emac.c b/drivers/net/ethernet/allwinner/sun4i-emac.c
index 2f516b950..2f990d0a5 100644
--- a/drivers/net/ethernet/allwinner/sun4i-emac.c
+++ b/drivers/net/ethernet/allwinner/sun4i-emac.c
@@ -237,6 +237,7 @@ emac_alloc_dma_req(struct emac_board_info *db,
 
 static void emac_free_dma_req(struct emac_dma_req *req)
 {
+	dmaengine_desc_free(req->desc);
 	kfree(req);
 }
 
-- 
2.25.1

Re: [PATCH] net: ethernet: sun4i-emac: free dma descriptor

[Jakub Kicinski]

On Wed,  3 Sep 2025 15:49:39 +0800 Conley Lee wrote:
> In the current implementation of the sun4i-emac driver, when using DMA to
> receive data packets, the descriptor for the current DMA request is not
> released in the rx_done_callback.
> 
> Fix this by properly releasing the descriptor.

Reading the docs, it appears that the need to free the desc is tied to
setting descriptor reuse flag. Which this driver does not do. So I'm
unclear why this is needed, maybe the dma engine driver is doing
something strange?

Could you repost this, CC the dmaengine ML, Vinod and the appropriate
SoC maintainers?