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The palmas PMIC has two control lines that need to be muxed properly for things to work. The sys_nirq pin is used for interrupts, and msecure pin is used for enabling writes to some PMIC registers. Without these pins configured properly things can fail in mysterious ways. For example, we can't update the RTC registers on palmas PMIC unless the msecure pin is configured. And this is probably the reason why we had RTC missing from the omap5 dts file. According to "OMAP5430 ES2.0 Data Manual [Public] VErsion A (Rev. F)" swps052f.pdf, mux mode 1 is for sys_drm_msecure so in theory there's should be no need to configure it as a GPIO pin. However, it seems there are some reliability issues using the msecure mux mode. And the TI trees configure the msecure pin as GPIO out high instead. As the PMIC only cares that the msecure line is high to allow access to the RTC registers, let's use a GPIO hog as suggested by Nishanth Menon <nm@ti.com>. Also the use of the internal pull was considered but supposedly that may not be capable of keeping the line high in a noisy environment. If we ever see high security omap5 products in the mainline tree, those need to skip the msecure pin muxing and ignore setting the GPIO hog. Chances are the related pin mux registers are locked in that case and the msecure pin is managed by whatever software may be running in the ARM TrustZone. Who knows what the original intention of the msecure pin was. Maybe it was supposed to prevent the system time to be set back for some game demo modes to time out? Anyways, it seems that later PMICs like tps659037 have recycled this pin for "powerhold" and devices like beagle-x15 do not need changes to the msecure pin configuration. To avoid further confusion with TWL variant PMICs, beagle-x15 does not have a back-up battery for RTC palmas. Instead the mcp79410 RTC is used with rtc-ds1307 driver. There is a "powerhold" jumper j5 holes near the palmas PMIC, and shorting it seems to power up beagle-x15 automatically. It is unknown if it also has other side effects to the beagle-x15 power up sequence. Cc: stable@vger.kernel.org # v4.4 Signed-off-by: Tony Lindgren <tony@atomide.com> |
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| .. | ||
| boot | ||
| common | ||
| configs | ||
| crypto | ||
| firmware | ||
| include | ||
| kernel | ||
| kvm | ||
| lib | ||
| mach-alpine | ||
| mach-asm9260 | ||
| mach-at91 | ||
| mach-axxia | ||
| mach-bcm | ||
| mach-berlin | ||
| mach-clps711x | ||
| mach-cns3xxx | ||
| mach-davinci | ||
| mach-digicolor | ||
| mach-dove | ||
| mach-ebsa110 | ||
| mach-efm32 | ||
| mach-ep93xx | ||
| mach-exynos | ||
| mach-footbridge | ||
| mach-gemini | ||
| mach-highbank | ||
| mach-hisi | ||
| mach-imx | ||
| mach-integrator | ||
| mach-iop13xx | ||
| mach-iop32x | ||
| mach-iop33x | ||
| mach-ixp4xx | ||
| mach-keystone | ||
| mach-ks8695 | ||
| mach-lpc18xx | ||
| mach-lpc32xx | ||
| mach-mediatek | ||
| mach-meson | ||
| mach-mmp | ||
| mach-moxart | ||
| mach-mv78xx0 | ||
| mach-mvebu | ||
| mach-mxs | ||
| mach-netx | ||
| mach-nomadik | ||
| mach-nspire | ||
| mach-omap1 | ||
| mach-omap2 | ||
| mach-orion5x | ||
| mach-picoxcell | ||
| mach-prima2 | ||
| mach-pxa | ||
| mach-qcom | ||
| mach-realview | ||
| mach-rockchip | ||
| mach-rpc | ||
| mach-s3c24xx | ||
| mach-s3c64xx | ||
| mach-s5pv210 | ||
| mach-sa1100 | ||
| mach-shmobile | ||
| mach-socfpga | ||
| mach-spear | ||
| mach-sti | ||
| mach-stm32 | ||
| mach-sunxi | ||
| mach-tegra | ||
| mach-u300 | ||
| mach-uniphier | ||
| mach-ux500 | ||
| mach-versatile | ||
| mach-vexpress | ||
| mach-vt8500 | ||
| mach-w90x900 | ||
| mach-zx | ||
| mach-zynq | ||
| mm | ||
| net | ||
| nwfpe | ||
| oprofile | ||
| plat-iop | ||
| plat-omap | ||
| plat-orion | ||
| plat-pxa | ||
| plat-samsung | ||
| plat-versatile | ||
| probes | ||
| tools | ||
| vdso | ||
| vfp | ||
| xen | ||
| Kconfig | ||
| Kconfig-nommu | ||
| Kconfig.debug | ||
| Makefile | ||