> -----Original Message----- > From: Trent Piepho [mailto:[email protected]] > Sent: 2018年5月9日 4:11 > 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 Tue, 2018-05-08 at 05:29 +0000, Peng Fan wrote: > > > -----Original Message----- > > > From: Trent Piepho [mailto:[email protected]] > > > Sent: 2018年5月8日 6:07 > > > To: [email protected]; Peng Fan <[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 Thu, 2018-01-04 at 17:03 +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. > > 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. -Peng > > > > Due to an erratum in iMX7d it is necessary to wire the external > > > WDOG_B signal to the pmic to cycle power in order to reset the > > > board. The Linux IMX watchdog driver works when it does a reboot > > > via the watchdog, but this code does not. > > > > > > When the Linux drivers is configured for an external wdog signal, > > > using a DT property, it sets WCR_SRS to prevent the internal system > > > reset in response to watchdog triggering. When that is not done, as > > > in this patch, the internal reset appears to reset the wdog module > > > or iomux or something, which causes the imx7d to stop asserting the > > > external wdog signal. > > > > > > In my tests, this takes only about 2.4 µs. Such a short wdog_b > > > pulse does not appear to be sufficient to trigger the pmic to cycle power. > > > > > > When SRS is set, then the WDOG_B signal will remain asserted until > > > the POR_B input signal to the imx7d is asserted. I.e., until pmic > > > responds to the watchdog signal. _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
