> -----Original Message----- > From: Trent Piepho [mailto:[email protected]] > Sent: 2018年5月10日 3:22 > To: Peng Fan <[email protected]>; [email protected]; Anson > Huang <[email protected]>; [email protected]; > [email protected]; [email protected] > Cc: Fabio Estevam <[email protected]> > Subject: Re: [U-Boot,V2] imx: mx7: psci: add system reset support > > On Wed, 2018-05-09 at 01:13 +0000, Peng Fan wrote: > > > +0800, Anson Huang wrote: > > > > > > Add i.MX7 PSCI system reset support, linux kernel now can use > "reboot" > > > > > > command to reset system. > > > > > > > > > > > > > > > > +__secure void imx_system_reset(void) { > > > > > > + writew(1 << 2, WDOG1_BASE_ADDR); } > > > > > > > > > > This does not work properly on our board. > > > > > > > > You could try write 0x14 to WDOG1_BASE_ADDR to see whether it works. > > > > Here using (1 << 2) triggers both SRS and WDOG_B which seems wrong. > > > > > > It works when the Linux driver does that and appears to work > > > identically when uboot does it that way. > > > > > > Triggering both SRS and WDOG_B does not work as it causes a very > > > short wdog_b assertion. > > > > Yes. > > In case it wasn't clear, this code is in the new 2018.05 u-boot release and I > think > will cause a problem for any imx7d board using the typical reset erratum > option > of connecting wdog_b to a pfuze3000 pmic's pwrwon pin. > > An external watchdog monitor chip, I think as used on sabreD for instance, > might still respond to the short pulse and allow it work.
I understand this. > > > > There is a little difficulty here in just changing the code to use > > > WCR_WDE|WCR_SRS, as that would be wrong if the board does not use an > > > external signal. The Linux driver uses the device tree to determine > > > what to do, but this will not work for PSCI. > > > > U-Boot need parse the device tree and configure the WDOG accordingly. > > Yes, but consider the difficulties: > > There could be multiple Linux device trees, e.g. in a FIT image and chosen > based > on board revision. Should the PSCI code use the u-boot device tree? Which > would then need to also have this board revision support. Or should it use > the > Linux DT, which it would need to get information from when the kernel DT is > prepared before boot? > > Of the five external watchdog signals from the iMX7d, which one should be > used? > I believe each imx watchdog configured in Linux will register a reset handler > that are called in turn, so Linux should handle this ok. The uboot PSCI > currently > assumes wdog1 is the correct one to use. > > The Linux driver interfaces with Linux pinctl to iomux the watchdog signal. > The > PSCI code is assuming the wdog signal is correctly muxed. > Default iomux values doesn't have any wdog signal routed to a pin. > > Not impossible, but it is not so simple as the original three lines of code > might > have made it seem at first glance. The imx_system_reset might could be moved to per board specific. Then the board owner could have their own imeplementation. Stefano, what do you think? > > If one has the Linux imx watchdog driver working, to use as watchdog, then one > gets a wdog system reset for free with all the above taken care of. Which > makes me wonder if disabling the PSCI reset might not be a better option in > that > situration. Just wonder, since you are using psci, you have the power related code ready? -Peng. _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
