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Commit b2c8bb06 authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Greg Kroah-Hartman
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dmaengine: mv_xor_v2: fix tx_submit() implementation 



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.

Fixes: 19a340b1 ("dmaengine: mv_xor_v2: new driver")
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d091850

drivers/dma/mv_xor_v2.c

+5 −17
Original line number Diff line number Diff line
@@ -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;

};



/**
@@ -213,18 +214,6 @@ static void mv_xor_v2_set_data_buffers(struct mv_xor_v2_device *xor_dev, 
	}

}



/*

 * 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.

 */
@@ -306,7 +295,6 @@ static irqreturn_t mv_xor_v2_interrupt_handler(int irq, void *data) 
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_descriptor *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);