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Subject[PATCH 3/3] [v2] dmaengine: dw-edma: fix endianess confusion
Date
When building with 'make C=1', sparse reports an endianess bug:

drivers/dma/dw-edma/dw-edma-v0-debugfs.c:60:30: warning: cast removes address space of expression
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: warning: incorrect type in argument 1 (different address spaces)
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: expected void const volatile [noderef] <asn:2>*addr
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: got void *[assigned] ptr
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: warning: incorrect type in argument 1 (different address spaces)
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: expected void const volatile [noderef] <asn:2>*addr
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: got void *[assigned] ptr
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: warning: incorrect type in argument 1 (different address spaces)
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: expected void const volatile [noderef] <asn:2>*addr
drivers/dma/dw-edma/dw-edma-v0-debugfs.c:86:24: got void *[assigned] ptr

The current code is clearly wrong, as it passes an endian-swapped word
into a register function where it gets swapped again. Just pass the variables
directly into lower_32_bits()/upper_32_bits().

Fixes: 7e4b8a4fbe2c ("dmaengine: Add Synopsys eDMA IP version 0 support")
Link: https://lore.kernel.org/lkml/20190617131820.2470686-1-arnd@arndb.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: remove unneeded local variables
---
drivers/dma/dw-edma/dw-edma-v0-core.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
index 97e3fd41c8a8..692de47b1670 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -195,7 +195,6 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
struct dw_edma_v0_lli __iomem *lli;
struct dw_edma_v0_llp __iomem *llp;
u32 control = 0, i = 0;
- u64 sar, dar, addr;
int j;

lli = chunk->ll_region.vaddr;
@@ -214,13 +213,11 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
/* Transfer size */
SET_LL(&lli[i].transfer_size, child->sz);
/* SAR - low, high */
- sar = cpu_to_le64(child->sar);
- SET_LL(&lli[i].sar_low, lower_32_bits(sar));
- SET_LL(&lli[i].sar_high, upper_32_bits(sar));
+ SET_LL(&lli[i].sar_low, lower_32_bits(child->sar));
+ SET_LL(&lli[i].sar_high, upper_32_bits(child->sar));
/* DAR - low, high */
- dar = cpu_to_le64(child->dar);
- SET_LL(&lli[i].dar_low, lower_32_bits(dar));
- SET_LL(&lli[i].dar_high, upper_32_bits(dar));
+ SET_LL(&lli[i].dar_low, lower_32_bits(child->dar));
+ SET_LL(&lli[i].dar_high, upper_32_bits(child->dar));
i++;
}

@@ -232,9 +229,8 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
/* Channel control */
SET_LL(&llp->control, control);
/* Linked list - low, high */
- addr = cpu_to_le64(chunk->ll_region.paddr);
- SET_LL(&llp->llp_low, lower_32_bits(addr));
- SET_LL(&llp->llp_high, upper_32_bits(addr));
+ SET_LL(&llp->llp_low, lower_32_bits(chunk->ll_region.paddr));
+ SET_LL(&llp->llp_high, upper_32_bits(chunk->ll_region.paddr));
}

void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
@@ -242,7 +238,6 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
struct dw_edma_chan *chan = chunk->chan;
struct dw_edma *dw = chan->chip->dw;
u32 tmp;
- u64 llp;

dw_edma_v0_core_write_chunk(chunk);

@@ -262,9 +257,10 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
SET_CH(dw, chan->dir, chan->id, ch_control1,
(DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));
/* Linked list - low, high */
- llp = cpu_to_le64(chunk->ll_region.paddr);
- SET_CH(dw, chan->dir, chan->id, llp_low, lower_32_bits(llp));
- SET_CH(dw, chan->dir, chan->id, llp_high, upper_32_bits(llp));
+ SET_CH(dw, chan->dir, chan->id, llp_low,
+ lower_32_bits(chunk->ll_region.paddr));
+ SET_CH(dw, chan->dir, chan->id, llp_high,
+ upper_32_bits(chunk->ll_region.paddr));
}
/* Doorbell */
SET_RW(dw, chan->dir, doorbell,
--
2.20.0
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