On Wed, Jun 4, 2014 at 10:54 AM, Sekhar Nori <nsekhar@xxxxxx> wrote: > On Wednesday 04 June 2014 01:55 PM, Yegor Yefremov wrote: >> On Wed, Jun 4, 2014 at 8:40 AM, Sekhar Nori <nsekhar@xxxxxx> wrote: >>> On Tuesday 03 June 2014 04:18 PM, Yegor Yefremov wrote: >>>> On Tue, Jun 3, 2014 at 9:57 AM, Yegor Yefremov >>>> <yegorslists@xxxxxxxxxxxxxx> wrote: >>>>> Kernel: 3.14, 3.15 (I haven't tried another kernels) >>>>> >>>>> As soon as I write something to my NAND flash (via cat image > >>>>> /dev/mtdblockx or ubiupdatevol) and make reboot or press a reset >>>>> button, I see only CCCCC and nothing happens before I make a power >>>>> cycle. Any idea? >>>> >>>> Just forgot to mention, that I was actually booting from MMC (mmc1). >>>> The boot sequence is UART0...XIP...MMC0...NAND. >>>> >>>> If I just mount ubifs partition as rootfs and change some files, I >>>> still can perform reboot and boot from MMC again. The issue seems to >>>> occur only, if I write to /dev/mtdblock directly. What can affect ROM >>>> boot so that it doesn't follow the boot sequence? >>> >>> Writing to sysboot bits in control_status register will make ROM change >>> boot sequence. Not sure why NAND driver should be changing these values. >>> Can you please verify that this register is indeed modified after the >>> NAND write? >> >> Can I read this register from userspace via debugfs? I can't find such >> entry so far. > > If not debugfs you can use devmem2[1] to read from userspace. You need > to provide physical address of the register. > >> I made another test: write to NAND and then make kexec. In this case I >> can successfully execute "reboot" afterwards. > > Okay. We need to monitor how sysboot values are changing between these > steps. devmem from busybox seems to work better. At least it delivers real values and not 0x0 as devmem2 does. Anyway the value doesn't change and looks as configured via resistors: # devmem 0x44E10040 32 0x00400304 I wonder, where can I issue NAND reset from userspace? This is one of the commands the kernel does during the initialization. Yegor -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
