On Fri, Dec 16, 2016 at 03:55:07PM +0000, Bryan O'Donoghue wrote: > On 16/12/16 15:00, Johan Hovold wrote: > > But in a static setup, you control what firmware you load, so you don't > > need it to be self-describing. > > That depends. > > Right now I don't see a good method for kernel and a firmware to agree > on ownership of GPIOs (and other shared resources) for example. I know > virtio/rproc (or some combination of the two) is supposed to be able to > do this. > > Just transmitting a manifest over an RPC link seems much simpler than > what I've seen of virtio/rproc so far - and I'm not convinced the two > together can describe as much as a manifest file. But remember that manifests come *from* the firmware (remote entity, module), but here it sounds like you want to be able pass a device-tree fragment or similar *to* the firmware. Manifests are used to describe what resources the modules provide, which wouldn't necessarily help in this case which seems to be about configuring the module (co-processor). > On some platforms (taking Edison as an example) you load a firmware that > basically just assumes it owns some pins. There's exactly zero > synchronisation between the two AMP processors (no type of message > passing to negotiate) between kernel and firmware (that I know of). > > So it's pretty easy to mess that type of setup up. Whereas if the > firmware returned a descriptor (or made requests for certain shared > resources) it would be a lot less brittle. > > Greybus (or another protocol) could be used to request allocation of a > GPIO from Linux to firmware, same with UART, i2c or another piece of > hardware that both sides of the message bus can own - but only one of > them should own at any one time. > > That's at least part of the problem I was looking at greybus to solve. Ok, but it sounds like what we have today would not necessarily help with that problem (apart from providing a messaging service). > Perhaps though I have a hammer and so everything looks like a nail > > http://www.urbandictionary.com/define.php?term=Irish%20Screwdriver Heh. :) Johan _______________________________________________ greybus-dev mailing list greybus-dev@xxxxxxxxxxxxxxxx https://lists.linaro.org/mailman/listinfo/greybus-dev
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