Date: Fri, 6 Jan 2017 16:40:21 -0200 From: "Dr. Rolf Jansen" <rj@obsigna.com> To: freebsd-arm@freebsd.org Subject: Re: BeagleBone Black MMC ordering clashes Message-ID: <F0D101AF-181B-4630-B539-C354C21538EC@obsigna.com> In-Reply-To: <1483722560.96230.10.camel@freebsd.org> References: <7D750433-59FC-4999-AC24-041683E17310@obsigna.com> <1483718084.96230.5.camel@freebsd.org> <0D800E14-799A-4926-AEF8-CD698D647E40@obsigna.com> <1483722560.96230.10.camel@freebsd.org>
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> Am 06.01.2017 um 15:09 schrieb Ian Lepore <ian@freebsd.org>: >=20 > On Fri, 2017-01-06 at 14:33 -0200, Dr. Rolf Jansen wrote: >>>=20 >>> Am 06.01.2017 um 13:54 schrieb Ian Lepore <ian@freebsd.org>: >>>=20 >>> On Fri, 2017-01-06 at 12:37 -0200, Dr. Rolf Jansen wrote: >>>>=20 >>>> The BeagleBone Black comes with 2 MMC facilities, one built-in >>>> (internal 4 GB) and one provided by a removable SD card. For >>>> unknown >>>> reasons the BBB defined on the removable SD card to be MMC0 and >>>> the >>>> internal flash memory is MMC0. >>>>=20 >>>> 1) In the first go, I dd'd the FreeBSD-12 BBB snapshot >>>> (20161221) >>>> onto a SD card and I was able to start the device from that card. >>>> gpart showed me that the device identifier of the SD card is >>>> mmcsd0 >>>> and that of the internal flash memory is mmcsd1. OK, that matches >>>> the >>>> already mentioned definitions. >>>>=20 >>>> 2) Now, I destroyed the partition of the internal mmcsd1 and >>>> created a new one: >>>>=20 >>>> =3D> 63 7552961 mmcsd1 MBR (3.6G) >>>> 63 8129 - free - (4.0M) >>>> 8192 8192 1 fat32 [active] (4.0M) >>>> 16384 7536640 2 freebsd (3.6G) >>>>=20 >>>> =3D> 0 7536640 mmcsd1s2 BSD (3.6G) >>>> 0 7536640 1 freebsd-ufs (3.6G) >>>>=20 >>>> 3) I copied over the contents of /boot/msdos from the external >>>> SD >>>> card to the msdosfs on mmcsd1s1 and I installed the FreeBSD 12 >>>> snapshot on mmcsd1s1a. Restarting the device from the internal >>>> flash >>>> and no external SD inserted with FreeBSD 12-CURRENT works well at >>>> the >>>> first glance. >>>>=20 >>>> 4) However, the internal flash got now the device identifier >>>> mmcsd0: >>>>=20 >>>> ... >>>> mmc0: No compatible cards found on bus >>>> ... >>>> mmcsd0: 4GB <MMCHC MMC04G 5.8 SN 82390DEC MFG 11/1998 by 112 >>>> 0x0000> at mmc1 48.0MHz/8bit/65535-block >>>> ... >>>>=20 >>>> I know, this is how FreeBSD deals with the device numbering, i.e. >>>> serial numbers starting at zero without particular meaning, and I >>>> know that we should not rely on the number ordering. >>>>=20 >>>> But it seems that the MMC device driver does cont on the external >>>> SD >>>> card is at MMC0 when I insert it into the BBB once it has been >>>> started from the internal flash. It seems to insist to assign the >>>> device ID mmcsd0, which results in the device ordering clash >>>> because >>>> mmcsd0 has been assigned to the internal flash at MMC1 (s. >>>> above). >>>>=20 >>>> In the moment, I can have both flash device active at the same >>>> time >>>> only when I start the BBB from the external SD. >>>>=20 >>>> I would be glad to hear suggestions on how to deal with the >>>> issue. At >>>> the end of the day, I want to start the device from the mostly >>>> static >>>> OS file system on the internal flash and keep the volatile data >>>> on >>>> the external SD. >>>>=20 >>>> Best regards >>>>=20 >>>> Rolf >>> The mmcsd0 identifier will be assigned to the first mmc device >>> found >>> that has a valid mmc or sd card. If the external slot has a card >>> in >>> it, it will become mmcsd0 because it gets probed first. If it has >>> no >>> card in it, the onboard eMMC becomes mmcsd0 because the sd slot >>> didn't >>> claim that device id. There is no way to change the order of >>> probing; >>> probing happens in order of the devices in the chip. The BBB >>> makers >>> decided to connect the external sd to the first device and the >>> onboard >>> eMMC to the second one. >> Thank you for rephrasing of what I wanted to say in my initial post: >>=20 >>>=20 >>>>=20 >>>> I know, this is how FreeBSD deals with the device numbering, i.e. >>>> serial numbers starting at zero without particular meaning, and I >>>> know that we should not rely on the number ordering. >> So, yes, this part is absolutely clear and understood. >>=20 >>>=20 >>> If you want the eMMC to be the root filesystem whether there is an >>> external sd card installed or not, the only solution is to use UFS >>> or >>> GPT labels instead of device names to refer to partitions in fstab. >> I do not rely on device identifiers in fstab on non of my numerous >> FreeBSD boxes, instead, I use the various sorts of labels ever since, >> and I continue to do it also with the BBB installation(s). >>=20 >> # df -h >> Filesystem Size Used Avail Capacity Mounted on >> /dev/ufs/SYSTEM 13G 875M 11G 7% / >> devfs 1.0K 1.0K 0B 100% /dev >> /dev/label/BOOT 4.0M 924K 3.1M 23% /boot/msdos >> tmpfs 50M 4.0K 50M 0% /tmp >>=20 >> However, this does not help in the given case, because the MMC device >> driver refuses to enumerate the SD card when inserted into a BBB that >> has been already started-up from the internal flash. So the question >> is, how can I get the SD card activated once inserted into a running >> system, and I would happily live with any device identifier for it, >> even let it mmcsd77 if only the device would be accessible by this. >>=20 >> Best regards >>=20 >> Rolf >=20 > Oh, you mean you boot from eMMC without an sd card, then later when = you > insert an sd card it's not detected? I've never tried that (I've = never > used the onboard eMMC at all), but it wouldn't surprise me that it's > broken. Yes, that is the problem. > It would imply we're not handling the card-detect properly, > probably because it's a gpio pin, and we didn't have good gpio support > back when I was working on the TI sdcard driver. Well, this might be related to an issues with the U-Boot/MLO facility. = Remember that I replaced the factory one on the eMMC by the one from the = FreeBSD 12.0-CURRENT(Beaglebone) image. Actually this allows me to boot = FreeBSD from the internal eMMC without an SD card, however with a = remarkable notice at the very beginning of the boot sequence: U-Boot SPL 2016.05 (Dec 21 2016 - 18:05:07) Trying to boot from MMC2 Card did not respond to voltage select! *** Warning - MMC init failed, using default environment The "Card did not respond" notice and the consecutive warning does not = appear when I boot from the SD card, instead I see another one about a = not supported property by the SD card:=20 U-Boot SPL 2016.05 (Dec 21 2016 - 18:05:07) Trying to boot from MMC1 Card doesn't support part_switch MMC partition switch failed *** Warning - MMC partition switch failed, using default environment Perhaps U-Boot disables/deactivates/turns-off something on the board = already in the very early stage. Perhaps I need to adapt the U-Boot = image for internal eMMC booting. > Yep, I just looked at the source, and there's no handling for gpio- > based sd card detect in the TI driver. Maybe I can find some time = this > weekend to add it, now that we have a better gpio infrastructure for > drivers to use. Many thanks in advance for spending your time. Best regards Rolf
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