From 056f6c87028544de934f27caf95aa1545d585767 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Fri, 10 Jul 2015 12:07:25 +0200
Subject: [PATCH] dmaengine: shdma: Make dummy shdma_chan_filter() always
return false
If CONFIG_SH_DMAE_BASE (which is required for DMA engine support for
legacy SH, SH/R-Mobile, and R-Car Gen1, but not for R-Car Gen2) is not
enabled, but CONFIG_RCAR_DMAC (for R-Car Gen2 DMA engine support) is,
and the DTS doesn't provide a "dmas" property for a device,
dma_request_slave_channel_compat() incorrectly succeeds, and returns a
DMA channel.
However, when trying to use that DMA channel later, it fails with:
rcar-dmac e6700000.dma-controller: rcar_dmac_prep_slave_sg: bad parameter: len=1, id=-22
(Fortunately most drivers can handle this failure, and fall back to
PIO)
The reason for this is that a NULL legacy filter function is used, which
actually means "all channels are OK", not "do not match".
If CONFIG_SH_DMAE_BASE is enabled (like in shmobile_defconfig, which
supports other SoCs besides R-Car Gen2), shdma_chan_filter() correctly
returns false, as no available channel on R-Car Gen2 matches a
shdma-base channel.
If the DTS does provide a "dmas" property, dma_request_slave_channel()
succeeds, and legacy filter-based matching is not used.
To fix this, change shdma_chan_filter from being NULL to a dummy
function that always returns false, like is done on other platforms.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
include/linux/shdma-base.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/shdma-base.h b/include/linux/shdma-base.h
index dd0ba502ccb3a..d927647e63503 100644
--- a/include/linux/shdma-base.h
+++ b/include/linux/shdma-base.h
@@ -128,7 +128,10 @@ void shdma_cleanup(struct shdma_dev *sdev);
#if IS_ENABLED(CONFIG_SH_DMAE_BASE)
bool shdma_chan_filter(struct dma_chan *chan, void *arg);
#else
-#define shdma_chan_filter NULL
+static inline bool shdma_chan_filter(struct dma_chan *chan, void *arg)
+{
+ return false;
+}
#endif
#endif
--
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