linux-kernel - [PATCH] Allow to use DMA_CTRL_REUSE flag for all channel types

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Date:   Fri, 28 Apr 2017 16:37:46 +0300
From:   Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
To:     dmaengine@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vinod.koul@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
Subject: [PATCH] Allow to use DMA_CTRL_REUSE flag for all channel types

In the current implementation dma_get_slave_caps is used to check
state of descriptor_reuse option. But dma_get_slave_caps includes
check if the channel supports slave transactions.
So DMA_CTRL_REUSE flag can be set (even for MEM-TO-MEM tranfers)
only if channel supports slave transactions.

Now we can use DMA_CTRL_REUSE flag for all channel types.
Also it allows to test reusing mechanism with simply mem-to-mem dma
test.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
---
 include/linux/dmaengine.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 5336808..92cf8b0 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1376,11 +1376,7 @@ static inline int dma_get_slave_caps(struct dma_chan *chan,
 
 static inline int dmaengine_desc_set_reuse(struct dma_async_tx_descriptor *tx)
 {
-	struct dma_slave_caps caps;
-
-	dma_get_slave_caps(tx->chan, &caps);
-
-	if (caps.descriptor_reuse) {
+	if (tx->chan->device->descriptor_reuse) {
 		tx->flags |= DMA_CTRL_REUSE;
 		return 0;
 	} else {
-- 
2.9.3