From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	=?UTF-8?q?Nuno=20S=C3=A1?= <nuno.sa@analog.com>,
	Michael Hennerich <michael.hennerich@analog.com>,
	Vinod Koul <vkoul@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 453/641] dma: dma-axi-dmac: fix SW cyclic transfers
Date: Tue, 24 Feb 2026 17:22:59 -0800
Message-ID: <20260225012359.491320421@linuxfoundation.org>
In-Reply-To: <20260225012348.915798704@linuxfoundation.org>
References: <20260225012348.915798704@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nuno Sá <nuno.sa@analog.com>

[ Upstream commit 9bd257181fd5c996d922e9991500ad27987cfbf4 ]

If 'hw_cyclic' is false we should still be able to do cyclic transfers in
"software". That was not working for the case where 'desc->num_sgs' is 1
because 'chan->next_desc' is never set with the current desc which means
that the cyclic transfer only runs once and in the next SOT interrupt we
do nothing since vchan_next_desc() will return NULL.

Fix it by setting 'chan->next_desc' as soon as we get a new desc via
vchan_next_desc().

Fixes: 0e3b67b348b8 ("dmaengine: Add support for the Analog Devices AXI-DMAC DMA controller")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
base-commit: 398035178503bf662281bbffb4bebce1460a4bc5
change-id: 20251104-axi-dmac-fixes-and-improvs-e3ad512a329c
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Link: https://patch.msgid.link/20251104-axi-dmac-fixes-and-improvs-v1-1-3e6fd9328f72@analog.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/dma-axi-dmac.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
index 5b06b0dc67ee1..e22639822045f 100644
--- a/drivers/dma/dma-axi-dmac.c
+++ b/drivers/dma/dma-axi-dmac.c
@@ -247,6 +247,7 @@ static void axi_dmac_start_transfer(struct axi_dmac_chan *chan)
 			return;
 		list_move_tail(&vdesc->node, &chan->active_descs);
 		desc = to_axi_dmac_desc(vdesc);
+		chan->next_desc = desc;
 	}
 	sg = &desc->sg[desc->num_submitted];
 
@@ -265,8 +266,6 @@ static void axi_dmac_start_transfer(struct axi_dmac_chan *chan)
 		else
 			chan->next_desc = NULL;
 		flags |= AXI_DMAC_FLAG_LAST;
-	} else {
-		chan->next_desc = desc;
 	}
 
 	sg->hw->id = axi_dmac_read(dmac, AXI_DMAC_REG_TRANSFER_ID);
-- 
2.51.0