>-----Original Message-----
>From: Lothar Waßmann [mailto:l...@karo-electronics.de]
>Sent: Wednesday, September 24, 2014 7:05 PM
>To: Lu Jingchang-B35083
>Cc: vinod.k...@intel.com; li...@arm.linux.org.uk; a...@arndb.de; linux-
>ker...@vger.kernel.org; dmaeng...@vger.kernel.org; linux-arm-
>ker...@lists.infradead.org
>Subject: Re: [PATCHv3] dmaengine: fsl-edma: fixup reg offset and hw S/G
>support in big-endian model
>
>Hi,
>
>Jingchang Lu wrote:
>> The offset of all 8-/16-bit register in big-endian eDMA model are
>s/register/registers/
>
>> swapped in a 32-bit size opposite those in the little-endian model.
>>
>> The hardware Scatter/Gather requires the subsequent TCDs in memory to
>> be auto loaded should retain little endian independent of the register
>> endian model, the dma engine will do the swap if need.
>>
>> This patch also use regular assignment for tcd variables r/w instead
>> of with io function previously that may not always be true.
>>
>> Signed-off-by: Jingchang Lu <jingchang...@freescale.com>
>> ---
>> changes in v3:
>> use unsigned long instead of u32 in reg offset swap cast to avoid
>warning.
>>
>> changes in v2:
>> simplify register offset swap calculation.
>> use regular assignment for tcd variables r/w instead of io function.
>>
>> drivers/dma/fsl-edma.c | 106
>> ++++++++++++++++++++++++++-----------------------
>> 1 file changed, 57 insertions(+), 49 deletions(-)
>>
>> diff --git a/drivers/dma/fsl-edma.c b/drivers/dma/fsl-edma.c index
>> 3c5711d..9ca55ee 100644
>> --- a/drivers/dma/fsl-edma.c
>> +++ b/drivers/dma/fsl-edma.c
>> @@ -177,16 +177,10 @@ struct fsl_edma_engine {
>> /*
>> * R/W functions for big- or little-endian registers
>> * the eDMA controller's endian is independent of the CPU core's endian.
>> + * for the big-endian IP module, the offset for 8-bit or 16-bit
>> + register
>s/for/For/
>
>> + * should also be swapped oposite to that in little-endian IP.
>s/oposite/opposite/
>
>[...]
>> @@ -459,20 +460,27 @@ static void fill_tcd_params(struct fsl_edma_engine
>*edma,
>> u16 csr = 0;
>>
>> /*
>> - * eDMA hardware SGs require the TCD parameters stored in memory
>> - * the same endian as the eDMA module so that they can be loaded
>> - * automatically by the engine
>> + * eDMA hardware SGs requires the TCDs to be auto loaded
>> + * in the little endian whenver the register endian model,
>"in little endian whatever the register endian model"
>
>> + * So we put the value in little endian in memory, waitting
>s/waitting/waiting/
>
>> + * for fsl_set_tcd_params doing the swap.
>fsl_set_tcd_params()
>
>
>
>Lothar Waßmann
>--
Thanks, I will amend them in the next version patch.
Best Regards,
Jingchang
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