[PATCH v3 1/6] dmaengine: mv_xor: fix big endian operation in register mode

[Andrew Lunn]

Hi Thomas

I ran the dmatest module on a kirkwood system. No obvious regressions.

Tested-by: Andrew Lunn <andrew at lunn.ch>

	   Andrew

On Tue, Jun 30, 2015 at 04:36:52PM +0200, Thomas Petazzoni wrote:
> Commit 6f166312c6ea2 ("dmaengine: mv_xor: add support for a38x command
> in descriptor mode") introduced the support for a feature that
> appeared in Armada 38x: specifying the operation to be performed in a
> per-descriptor basis rather than globally per channel.
> 
> However, when doing so, it changed the function mv_chan_set_mode() to
> use:
> 
>   if (IS_ENABLED(__BIG_ENDIAN))
> 
> instead of:
> 
>   #if defined(__BIG_ENDIAN)
> 
> While IS_ENABLED() is perfectly fine for CONFIG_* symbols, it is not
> for other symbols such as __BIG_ENDIAN that is provided directly by
> the compiler. Consequently, the commit broke support for big-endian,
> as the XOR_DESCRIPTOR_SWAP flag was not set in the XOR channel
> configuration register.
> 
> The primarily visible effect was some nasty warnings and failures
> appearing during the self-test of the XOR unit:
> 
> [    1.197368] mv_xor d0060900.xor: error on chan 0. intr cause 0x00000082
> [    1.197393] mv_xor d0060900.xor: config       0x00008440
> [    1.197410] mv_xor d0060900.xor: activation   0x00000000
> [    1.197427] mv_xor d0060900.xor: intr cause   0x00000082
> [    1.197443] mv_xor d0060900.xor: intr mask    0x000003f7
> [    1.197460] mv_xor d0060900.xor: error cause  0x00000000
> [    1.197477] mv_xor d0060900.xor: error addr   0x00000000
> [    1.197491] ------------[ cut here ]------------
> [    1.197513] WARNING: CPU: 0 PID: 1 at ../drivers/dma/mv_xor.c:664 mv_xor_interrupt_handler+0x14c/0x170()
> 
> See also:
> 
>   http://storage.kernelci.org/next/next-20150617/arm-mvebu_v7_defconfig+CONFIG_CPU_BIG_ENDIAN=y/lab-khilman/boot-armada-xp-openblocks-ax3-4.txt
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Fixes: 6f166312c6ea2 ("dmaengine: mv_xor: add support for a38x command in descriptor mode")
> Reviewed-by: Maxime Ripard <maxime.ripard at free-electrons.com>
> ---
> This fix should go in for 4.2.
> ---
>  drivers/dma/mv_xor.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
> index fbaf1ea..f1325f6 100644
> --- a/drivers/dma/mv_xor.c
> +++ b/drivers/dma/mv_xor.c
> @@ -162,10 +162,11 @@ static void mv_chan_set_mode(struct mv_xor_chan *chan,
>  	config &= ~0x7;
>  	config |= op_mode;
>  
> -	if (IS_ENABLED(__BIG_ENDIAN))
> -		config |= XOR_DESCRIPTOR_SWAP;
> -	else
> -		config &= ~XOR_DESCRIPTOR_SWAP;
> +#if defined(__BIG_ENDIAN)
> +	config |= XOR_DESCRIPTOR_SWAP;
> +#else
> +	config &= ~XOR_DESCRIPTOR_SWAP;
> +#endif
>  
>  	writel_relaxed(config, XOR_CONFIG(chan));
>  	chan->current_type = type;
> -- 
> 2.4.5
> 
> 
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