FAILED: patch "[PATCH] PCI: epf-mhi: Return 0, not remaining timeout, when eDMA ops" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 36bfc3642b19a98f1302aed4437c331df9b481f0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026050137-lesser-shaping-0e62@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 36bfc3642b19a98f1302aed4437c331df9b481f0 Mon Sep 17 00:00:00 2001
From: Daniel Hodges <[email protected]>
Date: Fri, 6 Feb 2026 15:05:29 -0500
Subject: [PATCH] PCI: epf-mhi: Return 0, not remaining timeout, when eDMA ops
complete

pci_epf_mhi_edma_read() and pci_epf_mhi_edma_write() start DMA operations and wait for completion with a timeout.

On successful completion, they previously returned the remaining timeout, which callers may treat as an error. In particular, mhi_ep_ring_add_element(), which calls pci_epf_mhi_edma_write() via mhi_cntrl->write_sync(), interprets any non-zero return value as failure.

Return 0 on success instead of the remaining timeout to prevent mhi_ep_ring_add_element() from treating successful completion as an error.

index f9cf18aa5b34..7f5326925ed5 100644
@@ -367,6 +367,8 @@ static int pci_epf_mhi_edma_read(struct mhi_ep_cntrl *mhi_cntrl,
 		dev_err(dev, "DMA transfer timeout\n");
 		dmaengine_terminate_sync(chan);
 		ret = -ETIMEDOUT;
+	} else {
+		ret = 0;
 	}
 
 err_unmap:

@@ -438,6 +440,8 @@ static int pci_epf_mhi_edma_write(struct mhi_ep_cntrl *mhi_cntrl,
 		dev_err(dev, "DMA transfer timeout\n");
 		dmaengine_terminate_sync(chan);
 		ret = -ETIMEDOUT;
+	} else {
+		ret = 0;
 	}
 
 err_unmap:

From: Daniel Hodges <[email protected]>

[ Upstream commit 36bfc3642b19a98f1302aed4437c331df9b481f0 ]

pci_epf_mhi_edma_read() and pci_epf_mhi_edma_write() start DMA operations and wait for completion with a timeout.

On successful completion, they previously returned the remaining timeout, which callers may treat as an error. In particular, mhi_ep_ring_add_element(), which calls pci_epf_mhi_edma_write() via mhi_cntrl->write_sync(), interprets any non-zero return value as failure.

Return 0 on success instead of the remaining timeout to prevent mhi_ep_ring_add_element() from treating successful completion as an error.

---
 drivers/pci/endpoint/functions/pci-epf-mhi.c | 4 ++++
 1 file changed, 4 insertions(+)

index 87154992ea11b..e5a7d1735649a 100644
@@ -331,6 +331,8 @@ static int pci_epf_mhi_edma_read(struct mhi_ep_cntrl *mhi_cntrl,
 		dev_err(dev, "DMA transfer timeout\n");
 		dmaengine_terminate_sync(chan);
 		ret = -ETIMEDOUT;
+	} else {
+		ret = 0;
 	}
 
 err_unmap:

@@ -402,6 +404,8 @@ static int pci_epf_mhi_edma_write(struct mhi_ep_cntrl *mhi_cntrl,
 		dev_err(dev, "DMA transfer timeout\n");
 		dmaengine_terminate_sync(chan);
 		ret = -ETIMEDOUT;
+	} else {
+		ret = 0;
 	}
 
 err_unmap:

2.53.0