On Tue, Nov 15, 2016 at 1:35 PM, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxx> wrote: > On Tue, Nov 15, 2016 at 12:27:53PM -0800, Tim Harvey wrote: >> On Mon, Nov 14, 2016 at 11:08 AM, Russell King - ARM Linux >> <linux@xxxxxxxxxxxxxxx> wrote: >> > So, someone merged a patch which makes mmcblk devices follow the >> > host controller numbering. >> > >> > Now my cubox-i fails to boot correctly because the SD card in the >> > _only_ SD card slot now gets called "mmcblk1" and not "mmcblk0". >> > >> > USDHC1 is wired to the on-microsom WiFi, and never has anything >> > remotely near a SD card or eMMC present. So, this change is >> > confusing on these platforms. >> > >> > Moreover, this is _going_ to break SolidRun distros if people upgrade >> > their kernels. >> > >> > It may be appropriate for eMMC, but it's not appropriate everywhere. >> > >> > This is a user visible _regression_ in 4.9-rc. Whoever did this, >> > please revert whatever change caused this, and next time limit it >> > to only eMMC. >> > >> > Thanks. >> >> I see the same thing on newer kernels, which is why I asked the >> question. I didn't expect (or even want honestly) a non mmcblk0 boot >> device and was looking for a way to control that via dt. Now I'm >> understanding that to avoid this kind of bootloader/kernel dependence >> issue I should be using UUID's to identify the boot device. >> >> >From my testing it looks like the change your looking for occurred >> some time ago and is somewhere between 4.5 and 4.6 and not a 4.9 >> regression specifically. > > That depends how you look at it. Yes, there's a change in 4.5 to 4.6 > which ties the block device number to the host device index, but that's > really only part of the story here. > > 4.8 definitely identifies the SD card in iMX6 usdhc2 as "mmcblk0". > 4.9-rc identifies the SD card as "mmcblk1". This makes it a 4.9 change > of behaviour - there can be no argument about that. > > Now, digging further into this today, it appears that: > > v4.8: usdhc2 was probed first, and is given mmc0. > usdhc1 is probed second, and is given mmc1. > > v4.9-rc: usdhc1 is probed first, and is given mmc0. > usdhc2 is probed second, and is given mmc1. > > I haven't yet been able to figure out why there's been this change > of probe order. There's no change that I can see in the iMX6 DT > files that would account for this. > I bisected it and the commit your looking for is 9aaf3437aa72ed5370bf32c99580a3fa2c330e3d Tim -- 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
