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. Thanks, Sekhar [1] www.lartmaker.nl/lartware/port/devmem2.c -- 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
