On 2016-11-16 06:45, Ulf Hansson wrote: > On 28 October 2016 at 17:37, Mark Rutland <mark.rutland@xxxxxxx> wrote: >> On Fri, Oct 28, 2016 at 08:23:04AM -0700, Tim Harvey wrote: >>> Greetings, >>> >>> I have an IMX6 board that has the following: >>> sdhc1: mmc0: sdio radio >>> sdhc2: mmc1: /dev/mmcblk1: microSD connector >>> sdhc3: mmc2: /dev/mmcblk2: on-board eMMC >>> >>> I would like to have sdhc3 registered as /dev/mmcblk0 and sdhc2 >>> registered as /dev/mmcblk1 so that permanent storage is the first >>> mmcblk device as I think this is more intuitive however currently >>> these get instanced in the order they appear in the imx6qdl.dtsi >>> device-tree configuration and are not able to be mapped the way I want >>> them in my dts file. >>> >>> Is there a way, or if not is there a desire for a way, to specify the >>> order of /dev/mmcblk devices via device-tree? >> >> As with many other devices, there is no standard way of controlling the >> Linux enumeration (and given the ID space is shared with other dynamic >> devices it's not something that could generally work). >> >> These should be refererd to by UUID if possible. >> >> If not, we could cosider adding a by-dt-path or something like that. > > So does that mean you think using "DT aliases" would be okay? As > Javier pointed out, there have been some attempts [1] for that, but > they didn't make it. > Perhaps we need to re-consider, and if so please re-review the DT > bindings patch from that series. I really would like to see some sort of stable MMC block device ordering. by-dt-path solutions requires initramfs, which adds complexity and boot time. Both not very welcome in simple embedded devices. PARTUUID is relying on a particular instance of a partition, which is not the same as to say boot from the second partition of device X. The main problem I see in my patchset is that it works around the fact MMC is a bus. Adding the mmc controller number to the block device name would avoid that issue (mmc0blk0...), not sure if a such a drastic change would be acceptable. -- Stefan -- 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
