Messages in this thread | | | From | Grant Likely <> | Date | Fri, 9 Nov 2012 12:06:02 +0000 | Subject | Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2) |
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On Mon, Nov 5, 2012 at 11:22 PM, Tony Lindgren <tony@atomide.com> wrote: > Hi, > > * Tabi Timur-B04825 <B04825@freescale.com> [121105 13:42]: >> On Mon, Nov 5, 2012 at 2:40 PM, Grant Likely <grant.likely@secretlab.ca> wrote: >> >> > Jane is building custom BeagleBone expansion boards called 'capes'. She >> > can boot the system with a stock BeagleBoard device tree, but additional >> > data is needed before a cape can be used. She could replace the FDT file >> > used by U-Boot with one that contains the extra data, but she uses the >> > same Linux system image regardless of the cape, and it is inconvenient >> > to have to select a different device tree at boot time depending on the >> > cape. >> >> What's wrong with having the boot loader detect the presence of the >> Cape and update the device tree accordingly? We do this all the time >> in U-Boot. Doing stuff like reading EEPROMs and testing for the >> presence of hardware is easier in U-Boot than in Linux. >> >> For configurations that can be determined by the boot loader, I'm not >> sure overlays are practical. > > I guess the beaglebone capes could be stackable and hotpluggable if > handled carefully enough.
And even if it can't on the beaglebone, it will happen somewhere else. I don't want to exclude that use-case just because nobody thought about it.
g.
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