On Fri, Jan 25, 2019 at 11:30:54AM -0500, John David Anglin wrote: > This also makes me wonder about this SD interrupt: > 43: 0 0 GPIO1 3 Edge d00d0000.sdhci cd > Many poeple have trouble with SD cards on reboot.
[off topic, but a relevant reply to the above] Very likely unrelated to edge interrupts. For a signal that goes low when a card is inserted and high when removed, you really need an edge interrupt to avoid flooding the CPU with a "stuck" interrupt - if you were to use an active low interrupt for card detection, and the signal is pulled low by card insertion, the interrupt remains active until you remove the card! In any case, I've seen the same with some early SolidRun platforms when using high speed modes. Most issues with SD cards at reboot is where the card is left in low voltage/high speed mode, the reboot happens, and then you try to talk to it in low-speed mode (as required by the specs for card detection/ initialisation) and they don't respond. The only way out of that is to reset the card - and the only way to reset the card is to remove power from it. If you're lucky enough to have a "regulator" which can be switched off at reboot, that may not be sufficient - if there's a capacitor on the SD card's supply line downstream from the regulator, the card can be drawing soo little current that the voltage doesn't fall sufficiently to cause the card to power down. If you don't have any means to reset the card like that, then the only workaround is to reduce the maximum speed - and avoid going to 1.8V signalling mode. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
