Patch "dmaengine: mv_xor_v2: fix tx_submit() implementation" has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

dmaengine: mv_xor_v2: fix tx_submit() implementation

to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dmaengine-mv_xor_v2-fix-tx_submit-implementation.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Thomas Petazzoni <[email protected]>
Date: Fri, 5 May 2017 11:57:48 +0200
Subject: dmaengine: mv_xor_v2: fix tx_submit() implementation

From: Thomas Petazzoni <[email protected]>

commit 44d5887a8bf1e86915c8ff647337cb138149da82 upstream.

The mv_xor_v2_tx_submit() gets the next available HW descriptor by calling mv_xor_v2_get_desq_write_ptr(), which reads a HW register telling the next available HW descriptor. This was working fine when HW descriptors were issued for processing directly in tx_submit().

However, as part of the review process of the driver, a change was requested to move the actual kick-off of HW descriptors processing to ->issue_pending(). Due to this, reading the HW register to know the next available HW descriptor no longer works.

So instead of using this HW register, we implemented a software index pointing to the next available HW descriptor.

---
 drivers/dma/mv_xor_v2.c |   22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)

@@ -161,6 +161,7 @@ struct mv_xor_v2_device {
 	struct mv_xor_v2_sw_desc *sw_desq;
 	int desc_size;
 	unsigned int npendings;
+	unsigned int hw_queue_idx;
 };
 
 /**

@@ -214,18 +215,6 @@ static void mv_xor_v2_set_data_buffers(s
 }
 
 /*
- * Return the next available index in the DESQ.
- */
-static int mv_xor_v2_get_desq_write_ptr(struct mv_xor_v2_device *xor_dev)
-{
-	/* read the index for the next available descriptor in the DESQ */
-	u32 reg = readl(xor_dev->dma_base + MV_XOR_V2_DMA_DESQ_ALLOC_OFF);
-
-	return ((reg >> MV_XOR_V2_DMA_DESQ_ALLOC_WRPTR_SHIFT)
-		& MV_XOR_V2_DMA_DESQ_ALLOC_WRPTR_MASK);
-}
-
-/*
  * notify the engine of new descriptors, and update the available index.
  */
 static void mv_xor_v2_add_desc_to_desq(struct mv_xor_v2_device *xor_dev,

@@ -306,7 +295,6 @@ static irqreturn_t mv_xor_v2_interrupt_h
 static dma_cookie_t
 mv_xor_v2_tx_submit(struct dma_async_tx_descriptor *tx)
 {
-	int desq_ptr;
 	void *dest_hw_desc;
 	dma_cookie_t cookie;
 	struct mv_xor_v2_sw_desc *sw_desc =

@@ -322,15 +310,15 @@ mv_xor_v2_tx_submit(struct dma_async_tx_
 	spin_lock_bh(&xor_dev->lock);
 	cookie = dma_cookie_assign(tx);
 
-	/* get the next available slot in the DESQ */
-	desq_ptr = mv_xor_v2_get_desq_write_ptr(xor_dev);
-
 	/* copy the HW descriptor from the SW descriptor to the DESQ */
-	dest_hw_desc = xor_dev->hw_desq_virt + desq_ptr;
+	dest_hw_desc = xor_dev->hw_desq_virt + xor_dev->hw_queue_idx;
 
 	memcpy(dest_hw_desc, &sw_desc->hw_desc, xor_dev->desc_size);
 
 	xor_dev->npendings++;
+	xor_dev->hw_queue_idx++;
+	if (xor_dev->hw_queue_idx >= MV_XOR_V2_DESC_NUM)
+		xor_dev->hw_queue_idx = 0;
 
 	spin_unlock_bh(&xor_dev->lock);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/dmaengine-mv_xor_v2-properly-handle-wrapping-in-the-array-of-hw-descriptors.patch queue-4.11/dmaengine-mv_xor_v2-enable-xor-engine-after-its-configuration.patch queue-4.11/dmaengine-mv_xor_v2-set-dma-mask-to-40-bits.patch queue-4.11/dmaengine-mv_xor_v2-do-not-use-descriptors-not-acked-by-async_tx.patch queue-4.11/dmaengine-mv_xor_v2-handle-mv_xor_v2_prep_sw_desc-error-properly.patch queue-4.11/dmaengine-mv_xor_v2-remove-interrupt-coalescing.patch queue-4.11/dmaengine-mv_xor_v2-fix-tx_submit-implementation.patch