On Mon, Sep 09, 2013 at 09:59:26AM -0400, Matt Porter wrote: > On Mon, Sep 09, 2013 at 02:51:13PM +0100, Jonathan Austin wrote: > > Hi Matt, > > > > On 09/09/13 14:31, Matt Porter wrote: > > >On Sun, Sep 08, 2013 at 01:12:26PM +0200, Koen Kooi wrote: > > >>The BeagleBone Black is basically a regular BeagleBone with eMMC and HDMI added, > > >>so create a common dtsi both can use. > > >> > > >>IMPORTANT: booting the existing am335x-bone.dts will blow up the HDMI transceiver > > >>after a dozen boots with an uSD card inserted because LDO will be at 3.3V instead > > >>of 1.8. > > >> > > >>MMC support for AM335x still isn't in, so only the LDO change has been added. > > >> > > >>Signed-off-by: Koen Kooi <koen@xxxxxxxxxxxxxxxxxxxxx> > > > > > >Tested-by: Matt Porter <matt.porter@xxxxxxxxxx> > > > > > >Works fine for me on tip and 3.11. I did notice a regression in musb (worked > > >on 3.11, now failing to probe but this is not related to your new dts as it > > >happens on am335x-bone.dts too, assuming merge window volatility). One nit, > > >git-am picked up a whitespace error on that extra line at EOF so you should > > >trim that out. > > > > > >Only thing is...for a clear bug like this that will destroy hardware, it > > >should be marked Cc: stable@xxxxxxxxxxxxxxx to be picked up in stable. > > > > > > > If I've understood Koen correctly then what he's saying is that if > > you *were* to use the current (before this patch) am335x-bone.dts on > > a Beagle Bone Black (which would be wrong, as that's not the board > > you have...) then things would break. > > > > I don't see that this patch fixes that - as far as I can see, even > > after the patch, using am335x-bone.dts with a Bone Black will risk > > the damage? > > > > If so, I don't think this is a 'stable fix' kind of thing, as it > > doesn't actually fix the problem? > > It fixes the problem by providing the correct dts for BBB which the > vendor tree has had for sometime. In the absence of a specific dts > for BBB, it appears everybody (TI and OMAP maintainers, included) > has assumed that am335x-bone.dts is correct and safe. > > I'm sure there's plenty of systems represented in dts/* where you > could cause damage by loading another dtb for a similar board from > the same SoC family...it's a common risk if you get the wrong dtb > with more-or-less arbitrary regulator settings. Sorry to reply to myself, but I probably didn't make it 100% clear as to why this effectively fixes the problem. Both mainline u-boot *and* the vendor u-boot have findfdt implemented to load an am335x-boneblack.dtb based on board detection. Hopefully this makes it clear why this fixes a bug in the kernel. If you use appended dtb to include the wrong one, well, you shouldn't be using appended dtb. It's a *hack* and loading it separately works fine if you use the U-Boot that ships with BBB or mainline. -Matt > > Koen - is there a way for a booting kernel to detect which board it > > is on and avoid any potential damage if someone gives it the wrong > > DT? > > > > Jonny > > > > >-Matt > > > > > >_______________________________________________ > > >linux-arm-kernel mailing list > > >linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > >http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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
