On Tue, May 12, 2015 at 02:07:21PM +0200, Martin Sperl wrote: > On 2015-05-12 12:20, Mark Brown wrote: > >We essentially have that; anything looking at a DMA mapped transfer had > >better cope. > I believe you miss my point: No, I don't. > a) with SPI_MASTER_MUST_ we will always allocate the buffer - we do not In the current implementation, we can always change that in the future. > And inside __spi_map_msg we can just add some code to create the simple > scatter-gather mapping using a single preallocated page - so something > along the lines (assuming that either tx_buf or rx_buf must be set): Yes, to repeat what I said earlier I'm hoping someone with a need for this will implement it. > So the extra flag seems to be to be a "safer" approach and it also > states more explicitly the needs of the driver. I think it's easier to either have drivers handle scatterlists or not rely on the flags for PIO and work harder if the code is looking complicated.
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