linux-kernel - [PATCH V6 20/33] csky/dma: fix up dma

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Date:   Fri, 28 Sep 2018 08:51:17 +0800
From:   Guo Ren <ren_guo@...ky.com>
To:     akpm@...ux-foundation.org, arnd@...db.de,
        daniel.lezcano@...aro.org, davem@...emloft.net,
        gregkh@...uxfoundation.org, jason@...edaemon.net,
        marc.zyngier@....com, mark.rutland@....com,
        mchehab+samsung@...nel.org, peterz@...radead.org, robh@...nel.org,
        robh+dt@...nel.org, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        devicetree@...r.kernel.org, green.hu@...il.com,
        Guo Ren <ren_guo@...ky.com>
Subject: [PATCH V6 20/33] csky/dma: fix up dma_mapping error

The arch_sync_dma_for_cpu()/arch_sync_dma_for_device() implementation is
broken for some combinations that end up in a BUG() instead of performing
the necessary flushes.

The implementation of arch should follow the following rules:
         map             for_cpu         for_device      unmap
 TO_DEV  writeback       none            writeback       none
 TO_CPU  invalidate      invalidate*     invalidate      invalidate*
 BIDIR   writeback       invalidate      writeback       invalidate

Link: https://lore.kernel.org/lkml/20180518215548.GH17671@n2100.armlinux.org.uk/
Signed-off-by: Guo Ren <ren_guo@...ky.com>
---
 arch/csky/mm/dma-mapping.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/csky/mm/dma-mapping.c b/arch/csky/mm/dma-mapping.c
index 16c2087..30a2041 100644
--- a/arch/csky/mm/dma-mapping.c
+++ b/arch/csky/mm/dma-mapping.c
@@ -217,7 +217,8 @@ void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
 		break;
 	case DMA_FROM_DEVICE:
 	case DMA_BIDIRECTIONAL:
-		BUG();
+		dma_wbinv_range(vaddr + offset, vaddr + offset + size);
+		break;
 	default:
 		BUG();
 	}
@@ -240,7 +241,7 @@ void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
 
 	switch (dir) {
 	case DMA_TO_DEVICE:
-		BUG();
+		break;
 	case DMA_FROM_DEVICE:
 	case DMA_BIDIRECTIONAL:
 		dma_wbinv_range(vaddr + offset, vaddr + offset + size);
-- 
2.7.4