On Thu, Feb 7, 2013 at 2:07 PM, Fabio Estevam <[email protected]> wrote: > On Thu, Feb 7, 2013 at 12:39 PM, Otavio Salvador > <[email protected]> wrote: >> On Thu, Feb 7, 2013 at 12:28 PM, Fabio Estevam >> <[email protected]> wrote: >>> On a mx6qsabresd revision C board with rev1.2 mx6q, the system gets >>> resetted and it is not able >>> to reach the Linux prompt. >>> >>> Clearing the PDE - Power Down Enable bit fixes the problem. >>> >>> Signed-off-by: Fabio Estevam <[email protected]> >> >> What is not clear to me is why this affects only revision C of the >> board. Is it clear for you? > > Yes, I investigated this further and I see that on mx6qsabresd revB > the watchdog does not cut power to the mx6. > > For example: > > - On mx6qsabresd revB: > > U-Boot > reset > resetting ... > > > U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46) > > CPU: Freescale i.MX6Q rev1.1 at 792 MHz > Reset cause: WDOG > Board: MX6Q-SabreSD > DRAM: 1 GiB > MMC: FSL_SDHC: 0, FSL_SDHC: 1, FSL_SDHC: 2 > *** Warning - bad CRC, using default environment > In: serial > Out: serial > Err: serial > Net: FEC [PRIME] > Warning: FEC using MAC address from net device > > Hit any key to stop autoboot: 0 > U-Boot > > > - On mx6qsabresd revC: > > U-Boot > reset > resetting ... > > > U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46) > > CPU: Freescale i.MX6Q rev1.1 at 792 MHz > Reset cause: POR > Board: MX6Q-SabreSD > DRAM: 1 GiB > MMC: FSL_SDHC: 0, FSL_SDHC: 1, FSL_SDHC: 2 > *** Warning - bad CRC, using default environment > In: serial > Out: serial > Err: serial > Net: FEC [PRIME] > Warning: FEC using MAC address from net device > > Hit any key to stop autoboot: 0 > U-Boot > > > So the watchdog reset happens on both revisions, but only on revC it > causes a POR due to its POR/watchdog circuitry. > > So in order to fix this: > > 1. We can always clear Power Down Enable (PDE) bit as I did on this > patch and how it is done on FSL U-boot. > > 2. Check the board revision and only clear (PDE) for revC board. > > I would prefer number 1. as if someone copies the schematics of a revC > board, but does not burn the fuses to indicate that their hardware > behaves as a mx6qsabresd revC, then the reset problem will occur on > their own board. > > I can also improve the commit log of the original patch to provide more > details.
Yes; I think an improved commit log would be handy. -- Otavio Salvador O.S. Systems E-mail: [email protected] http://www.ossystems.com.br Mobile: +55 53 9981-7854 http://projetos.ossystems.com.br _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
