On Mon, Jun 18, 2018 at 09:45:51AM +0200, Linus Walleij wrote: > This is a proposal for how to handle the non-discoverable > 96boards plug-in expansion boards called "mezzanines" in the > Linux kernel. It is a working RFC series meant for discussion > at the moment. > > The RFC was done on the brand new Ultra96 board from Xilinx > with a Secure96 mezzanine expansion board. The main part > is in patch 4, the rest is enabling and examples. > > The code can be obtained from here: > https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git/log/?h=ultra96 > > You can for example probably augment the DTS file for any > upstream-supported 96board and get the Secure96 going with > it with minor efforts. Like other commenters I'm rather like using C to solve this, and your comments Big Upfront Design are good backup in term of convincing me. > TODO: > > - Proper device tree bindings for the connector, for now > look at the example. > > - Discuss whether to actually do this or just take it all and > flush it down the drain because the community doesn't like > it. I'm not one of those especially infatuated with my own code, > I always stay by the old programming project management mantra > to calculate to make one version and throw it away as stepping > stone to a good final design. > > - Placement: putting this in drivers/bus is just an example. > drivers/platform/96boards-mezzanines is fine too, maybe better? > > - I am especially curious about input from Andy and Mika from > the Intel/ACPI camp on what they have seen for non-discoverable > plug-in boards. Does this problem even exist in the Intel > world, or not... I'm also interested in the "what about ACPI" question? Using C makes describing a board in ACPI fairly easy. AFAICT allocating IDs to a board rather than its included components is fairly natural for ACPI. However I'm too ignorant to be able to figure out if the expansion connector itself could/should be described in the tables (e.g. if connector is a bus and the board is[1] a device, could the bus driver be instantiated in a reasonable way). Daniel. [1] ... or becomes a device, based on feedback in this thread ;-) -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
