linux-kernel - [net-next PATCH RFC 15/26] arch/openrisc: Add option to skip DMA sync as a part of mapping

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Message-ID: <20161024120546.16276.32687.stgit@ahduyck-blue-test.jf.intel.com>
Date:   Mon, 24 Oct 2016 08:05:46 -0400
From:   Alexander Duyck <alexander.h.duyck@...el.com>
To:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc:     Jonas Bonn <jonas@...thpole.se>, davem@...emloft.net,
        brouer@...hat.com
Subject: [net-next PATCH RFC 15/26] arch/openrisc: Add option to skip DMA
 sync as a part of mapping

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Cc: Jonas Bonn <jonas@...thpole.se>
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---
 arch/openrisc/kernel/dma.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
index 140c991..906998b 100644
--- a/arch/openrisc/kernel/dma.c
+++ b/arch/openrisc/kernel/dma.c
@@ -141,6 +141,9 @@
 	unsigned long cl;
 	dma_addr_t addr = page_to_phys(page) + offset;
 
+	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+		return addr;
+
 	switch (dir) {
 	case DMA_TO_DEVICE:
 		/* Flush the dcache for the requested range */