Messages in this thread | | | Date | Wed, 24 Sep 2014 13:05:10 +0200 | From | Lothar Waßmann <> | Subject | Re: [PATCHv3] dmaengine: fsl-edma: fixup reg offset and hw S/G support in big-endian model |
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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.lu@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 -- ___________________________________________________________
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