Hi Geert and Simon, On Fri, Jun 9, 2017 at 4:40 PM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > Hi Simon, > > On Thu, Jun 8, 2017 at 3:09 PM, Simon Horman <horms+renesas@xxxxxxxxxxxx> wrote: >> Gen3 SoCs are now supported by the internal dmac variant of the SDHI driver. >> Remove them from the sys dmac variant where only PIO mode is supported. >> >> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx> > > Is it possible to fall back to PIO with the new DMAC driver? > If not, is this desirable? I believe R-Car Gen3 SDHI may depending on SoC use either on-chip bus mastering DMA or SYS-DMAC via DMA Engine. In both cases fall back to PIO is most likely valid. For any given SoC which is better of on-chip DMA or SYS-DMAC needs to be investigated together with IPMMU. Cheers, / magnus
