From: Juha Yrjola <juha.yrjola@solidboot.com>
Date: Thu, 29 Jan 2009 16:57:12 +0000 (-0800)
Subject: ARM: OMAP: Fix race in OMAP2/3 DMA IRQ handling
X-Git-Tag: firefly_0821_release~15666^2^2~6
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=320ce6f6fb3d95e02a183709e51d8a16a8b00e0a;p=firefly-linux-kernel-4.4.55.git

ARM: OMAP: Fix race in OMAP2/3 DMA IRQ handling

CSR must be cleared before invoking the callback.

If the callback function starts a new, fast DMA transfer on the same
channel, the completion status might lost if CSR is cleared after
the callback invocation.

Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
---

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index e77373c39f8c..bec8e363d545 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -1888,11 +1888,11 @@ static int omap2_dma_handle_ch(int ch)
 		status = dma_read(CSR(ch));
 	}
 
+	dma_write(status, CSR(ch));
+
 	if (likely(dma_chan[ch].callback != NULL))
 		dma_chan[ch].callback(ch, status, dma_chan[ch].data);
 
-	dma_write(status, CSR(ch));
-
 	return 0;
 }