On Sat, Sep 27, 2014 at 10:28:47AM +0100, Russell King - ARM Linux wrote: > On Sat, Sep 27, 2014 at 10:54:43AM +0200, Maxime Ripard wrote: > > The previous code was relying on the fact that the slave_caps were to be > > defined on a per channel basis. > > > > However, this proved to be a bit overkill, since every driver filling these so > > far were hardcoding it, disregarding which channel was actually given. > > > > Add these capabilities to the dma_device structure, so that drivers can just > > provide them at probe time, and be done with it. > > This is also buggy for the same reason as patch 6. Indeed > The only way to do this is to either have a flag day, fixing all drivers > at once (which isn't going to happen) or leave the caps code as-is, and > provide a library function which drivers can hook into the caps callback > which retrieves the information from dma_device. > > That way, DMA engine drivers which are using the new method can just > install the new function, and those which haven't been updated with > capabilities can carry on as they are, and are detectable to drivers. Which is pretty much the current behaviour, isn't it? > What would be acceptable is to have the DMA engine registration function > spot the lack of DMA caps function and print a warning at boot to > encourage people to add it. That would be an option too. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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