On Tue, Nov 16, 2010 at 4:21 PM, David VomLehn <[email protected]> wrote: > On 11/15/2010 10:57 PM, Grant Likely wrote: > > ... >> >> I'm not sure I completely follow you. Any memory described in a >> device_type="memory" node will by default be used as system RAM by >> Linux. If some of that region needs to be used for DMA buffers, then >> you'll need to make sure that when a driver allocates a buffer, that >> the buffer is made valid for DMA operations. How you do this is >> architecture specific. > > Okay, I think I've got this down > ... >> >> what does 'stbus' mean? If it is the hardware name for the bus, then >> it is probably a good choice. 'soc' is often used, but I'm not a big >> fan of that convention because it doesn't reflect the actual internal >> architecture of the chip. > > Yes, this is what STMicroelectronics call their bus, specifically "STBus". > Which looks like what the device tree calls a simple- bus.
To be specific, 'simple-bus' is a binding that means a simple memory mapped bus without any configuration required, but it is not the name of a bus. See ePAPR for the actual binding definition (which is pretty small). For completeness, the compatible value for this node should probably be: compatbile = "<socvendor>,<socmodel>-stbus", "simple-bus"; so that both the specific device device is detailed, as well as the fact that it is compatible with the simple-bus binding. As for the node name, "bus" would be fine. "stbus" would also be okay, as would "soc" or "soc-bus". The node name doesn't actually matter much as operating systems shouldn't ever depend on node names to determine behaviour, but the generic names recommended practice should still be followed as much as possible (see section 2.2.2 in ePAPR. This is also why "simple-bus" isn't a good name, because "simple-bus" represents the programming model, not a generic name of what the node is). .... and yes, I am aware that i get rather pedantic about this stuff. :-) g. _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
