On Sun, Sep 2, 2012 at 8:54 PM, Hein Tibosch <hein_tibo...@yahoo.es> wrote: > From: Hein Tibosch <hein_tibo...@yahoo.es> > > v4: now based and tested on 3.6-rc4 > > The dw_dmac driver was earlier adapted to do 64-bit transfers on the memory > side (see https://lkml.org/lkml/2012/1/18/52) > This works on ARM platforms but for AVR32 (AP700x) the maximum allowed > transfer > size is 32-bits. > This patch allows the arch code to set a new slave property max_mem_width to > limit the size. > > Allowable values are: > > #define DW_MEM_WIDTH_64 0 /* default */ > #define DW_MEM_WIDTH_32 1 /* e.g. for avr32 */ There are 4 options: 32, 64, 128, and 256 bits. I would prefer to see the value in conjunction with real value in the register, namely 2 for 32, 3 - 64, 4 - 128, 5 - 256.
> diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c > index d3c5a5a..311953c 100644 > --- a/drivers/dma/dw_dmac.c > +++ b/drivers/dma/dw_dmac.c > @@ -190,14 +190,14 @@ static void dwc_initialize(struct dw_dma_chan *dwc) > } > > /*----------------------------------------------------------------------*/ > - > -static inline unsigned int dwc_fast_fls(unsigned long long v) > +static inline unsigned int dwc_fast_fls(unsigned long long v, > + struct dw_dma_slave *dws) > { > /* > * We can be a lot more clever here, but this should take care > * of the most common optimization. > */ > - if (!(v & 7)) > + if (dws->max_mem_width == DW_MEM_WIDTH_64 && !(v & 7)) > return 3; > else if (!(v & 3)) > return 2; > @@ -655,7 +656,7 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t > dest, dma_addr_t src, > return NULL; > } > > - src_width = dst_width = dwc_fast_fls(src | dest | len); > + src_width = dst_width = dwc_fast_fls(src | dest | len, dws); And taking into consideration my upper comment, it could be easier to use min_t(unsigned int, max_mem_width, dwc_fast_fls(...)) here and there. > @@ -58,6 +58,9 @@ struct dw_dma_slave { > u32 cfg_lo; > u8 src_master; > u8 dst_master; > +#define DW_MEM_WIDTH_64 0 > +#define DW_MEM_WIDTH_32 1 /* e.g. for avr32 */ > + u8 max_mem_width; Might be I missed something, but why is it slave configuration? I think the controller (actually channel) structure is more suitable to keep that field inside. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/