Hi,
On Mon, Jun 17, 2019 at 14:17:47, Arnd Bergmann <a...@arndb.de> wrote:
> When building with 'make C=1', sparse reports an endianess bug:
I didn't know that option.
>
> 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. I assume that this
Sorry I didn't catch this, endianness-swapped word into a register
function where it gets swapped again?
Where?
> was simply ported from a non-Linux OS, and the swap was done incorrectly.
> Replace it with a cast to uintptr_t.
>
> Fixes: 7e4b8a4fbe2c ("dmaengine: Add Synopsys eDMA IP version 0 support")
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> ---
> drivers/dma/dw-edma/dw-edma-v0-core.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 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..d670ebcc37b3 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -195,7 +195,7 @@ 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;
> + uintptr_t sar, dar, addr;
Will this type assure variables sar, dar and addr are 64 bits?
> int j;
>
> lli = chunk->ll_region.vaddr;
> @@ -214,11 +214,11 @@ 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);
> + sar = (uintptr_t)child->sar;
Assuming the host is a big-endian machine and the eDMA on the endpoint
strictly requires the address to be little endian.
By not using cpu_to_le64(), the address to be written on the eDMA will be
in big-endian format, right? If so, that will break the driver.
> SET_LL(&lli[i].sar_low, lower_32_bits(sar));
> SET_LL(&lli[i].sar_high, upper_32_bits(sar));
> /* DAR - low, high */
> - dar = cpu_to_le64(child->dar);
> + dar = (uintptr_t)child->dar;
Ditto.
> SET_LL(&lli[i].dar_low, lower_32_bits(dar));
> SET_LL(&lli[i].dar_high, upper_32_bits(dar));
> i++;
> @@ -232,7 +232,7 @@ 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);
> + addr = (uintptr_t)chunk->ll_region.paddr;
Ditto.
> SET_LL(&llp->llp_low, lower_32_bits(addr));
> SET_LL(&llp->llp_high, upper_32_bits(addr));
> }
> @@ -262,7 +262,7 @@ 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);
> + llp = (uintptr_t)chunk->ll_region.paddr;
Ditto.
> 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));
> }
> --
> 2.20.0
