Date: Tue, 20 May 2014 04:52:16 +0300 From: "Sulev-Madis Silber (ketas)" <madis555@hot.ee> To: "Sulev-Madis Silber (ketas)" <madis555@hot.ee> Cc: freebsd-arm <freebsd-arm@FreeBSD.org> Subject: Re: BBB MMC / SD detection instability with U-Boot 2014.04 (CPU 1GHz) Message-ID: <537AB550.2090401@hot.ee> In-Reply-To: <537A050E.3040804@hot.ee> References: <537A050E.3040804@hot.ee>
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On 2014-05-19 16:20, Sulev-Madis Silber (ketas) wrote: > Hello. > > Although maybe I could write this as reply to some other message, I feel > like it might deserve separate one. > > I use U-Boot 2014.04 which sets CPU frequency to 1GHz, which seems nice. > Apart from inability to find eMMC in ubldr (SD card is always fine), now > I get whole different issues here. With 2013.04, I get occasional eMMC > failure I mentioned earlier. With 2014.04, it's very hard to get SD > devices detected at all. And I get all sorts of weird errors (megabytes > of boot logs from serial if anyone wishes to see). I'm aware how HW > clock changes can affect things like this, but I'm not exactly sure > where and what happens when this is done. If I boot with 2013.04, it's > ok again, if I switch to 2014.04 again, it's ok again for a while. It > really feels like it's overheating. After a while, it gets extremely > hard to get thing booted up. Both devices sometimes detect and sometimes > not. I get things like "no compatible cards found on bus" (mmc 0/1), or > things like "card at relative address x lost". Tried adding delays like > suggested earlier, but that doesn't help and now the issue seems > different. I get no other issues. System is very stable once it's booted > up. There are no hangs, panics... Everything works. I must mention that > I always use latest CURRENT. I didn't find a way to make kernel reboot > system when root mount fails, so I manually patched that option in. Last > time I got 11 failures before it booted up with both SD and eMMC found > (they don't fail same way every time, sometimes SD is missing, often > eMMC is missing). > > What would somebody else think about such issues? I don't have > experience in HW dev, I can only guess what goes wrong. And again, if it > boots, it works. And no component on BBB gets too warm to hold finger > there for long time, too (if that matters). I have 5V 2.5A PSU powering > it (but the PMIC should fail if voltage drops too much, etc, I read the > datasheet for that), I have few LEDs with resistors connected to GPIO > pins, two ~30cm wires that sit on table for input testing (resistors > there too, of course) and Nokia DKU-5 data cable for USB-TTL serial > console. If the board gets any ground, it's via this cable. But I don't > see how my HW config is related to this issue. And I don't change this > when I try different U-Boot's?! I don't have USB devices connected to > host port and nothing to other USB port too. I use old 64MB SD card to > help with booting (because of ubldr issues), not sure that matters, though. > > Thanks. > Now I have patch too. I feel much better now. It seems to fix everything. I'm sure that not all of those "delay"'s are needed. I got tired of failures and just put one into each place that seemed to need some waiting before continue. The side effect is that mmc detection doesn't take several seconds now, it's near instant. It also feels like device read speed is faster but I'm not entirely sure about that. So, what happened here? Slower CPU acted as some kind of limiter by itself? What's correct solution here? I'm only guessing but it at least works now. I don't think I've lost devices after this change, both SD card and eMMC device are always there. I should disable reboot on rootfs mount fail to fully confirm it. However that BUSTEST_W still gives error. Now, only ubldr-no-eMMC fix is needed. And / or U-Boot fix?
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