Messages in this thread | | | Date | Fri, 21 Sep 2012 15:03:12 -0400 | From | Matt Porter <> | Subject | Re: [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC |
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On Fri, Sep 21, 2012 at 07:47:21PM +0100, Russell King wrote: > On Fri, Sep 21, 2012 at 10:45:29PM +0530, S, Venkatraman wrote: > > On Thu, Sep 20, 2012 at 8:13 PM, Matt Porter <mporter@ti.com> wrote: > > > The EDMA DMAC has a hardware limitation that prevents supporting > > > scatter gather lists with any number of segments. Since the EDMA > > > DMA Engine driver sets the maximum segments to 16, we do the > > > same. > > > > > > Note: this can be removed once the DMA Engine API supports an > > > API to query the DMAC's segment limitations. > > > > > > > I wouldn't want to bind the properties of EDMA to omap_hsmmc as this patch > > suggests. Why don't we have a max_segs property, which when explicitly specified > > in DT, will override the default ? > > Why not have a generic way that DMA engine can export these kinds of > properties?
That's exactly what my note above is suggesting...
Something along the lines of:
struct slave_sg_caps { int max_segs; /* <0 is no limit */ }
struct slave_sg_cap * dmaengine_get_slave_sg_caps(struct dma_chan *chan);
I'm sure there are or will be other characteristics worth providing to slave drivers.
-Matt
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