Some Doc cleanup in PM, crypto, audio and DSS #556
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| ######################### | ||||||
| RTC-Only and RTC+DDR Mode | ||||||
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| ######################### | ||||||
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| AM437x supports two RTC modes, RTC+DDR and RTC-Only mode. RTC+DDR Mode is similar to the | ||||||
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Check warning on line 5 in source/linux/Foundational_Components/Power_Management/pm_rtc_ddr.rst
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| Suspend/Resume above but only supports wake by the Power Button present | ||||||
| on the board or from an RTC ALARM2 Event. RTC-Only mode supports the | ||||||
| same wake sources, however DDR context is not maintained so a wake event | ||||||
| causes a cold boot. | ||||||
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| RTC-Only mode is supported on: | ||||||
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| - AM437x GP EVM | ||||||
| - AM437x SK EVM | ||||||
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| RTC+DDR mode is supported on: | ||||||
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| - AM437x GP EVM | ||||||
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| .. rubric:: RTC+DDR Mode | ||||||
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| The first step in using RTC+DDR mode is to enable off mode by typing the | ||||||
| following at the command line: | ||||||
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| .. code-block:: console | ||||||
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| $ echo 1 > /sys/kernel/debug/pm_debug/enable_off_mode | ||||||
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| With off-mode enabled, a command to enter DeepSleep0 will now enter | ||||||
| RTC-Only mode: | ||||||
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There was a problem hiding this comment. This text appears to be incorrect. Under the "RTC+DDR Mode" section, it states that "a command to enter DeepSleep0 will now enter RTC-Only mode", but based on the context and section heading, it should describe entering RTC+DDR mode. The distinction between RTC-Only and RTC+DDR modes is explained later (lines 49-53) as depending on regulator configuration, but the text here should clarify that with proper regulator configuration, this enters RTC+DDR mode.
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| .. code-block:: console | ||||||
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| $ echo mem > /sys/power/state | ||||||
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| This method of entry only supports Power button as the wake source. | ||||||
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| To use the rtc as a wake source, after enabling off mode use the | ||||||
| following command: | ||||||
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| .. code-block:: console | ||||||
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| $ rtcwake -s <NUMBER OF SECONDS TO SLEEP> -d /dev/rtc0 -m mem | ||||||
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| Whether or not your board enters RTC-Only mode or RTC+DDR mode depends | ||||||
| on the regulator configuration and whether or not the regulator that | ||||||
| supplies the DDR is configured to remain on during suspend. This is | ||||||
| supported by the TPS65218 in use of the AM437x boards but not the | ||||||
| TPS65217 or TPS65910 present on AM335x boards. | ||||||
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| .. code-block:: dts | ||||||
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| tps65218: tps65218@24 { | ||||||
| reg = <0x24>; | ||||||
| compatible = "ti,tps65218"; | ||||||
| interrupts = <GIC_SPI 7 IRQ_TYPE_NONE>; /* NMIn */ | ||||||
| interrupt-parent = <&gic>; | ||||||
| interrupt-controller; | ||||||
| #interrupt-cells = <2>; | ||||||
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| ... | ||||||
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| dcdc3: regulator-dcdc3 { | ||||||
| compatible = "ti,tps65218-dcdc3"; | ||||||
| regulator-name = "vdcdc3"; | ||||||
| regulator-suspend-enable; | ||||||
| regulator-min-microvolt = <1500000>; | ||||||
| regulator-max-microvolt = <1500000>; | ||||||
| regulator-boot-on; | ||||||
| regulator-always-on; | ||||||
| }; | ||||||
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| ... | ||||||
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| }; | ||||||
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| Another important thing to make sure of is that you are using the proper | ||||||
| u-boot. A certain u-boot is required in order to support RTC+DDR mode | ||||||
| otherwise the following message appears during boot of the kernel: | ||||||
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| ``PM: bootloader does not support rtc-only!`` | ||||||
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| When building u-boot, rather than using ``am43xx_evm_config`` you must | ||||||
| use ``am43xx_evm_rtconly_config`` to support either RTC mode. | ||||||
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| .. rubric:: RTC-Only Mode | ||||||
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| RTC-Only mode does not maintain DDR context so placing a board into | ||||||
| RTC-only mode allows for very low power consumption after which a | ||||||
| supported wake source will cause a cold boot. RTC-Only mode is entered | ||||||
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Check failure on line 90 in source/linux/Foundational_Components/Power_Management/pm_rtc_ddr.rst
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| via the poweroff command. | ||||||
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| To wakeup from RTC-Only mode via an RTC alarm, a separate tool must be | ||||||
| used to program an RTC alarm prior to entering poweroff. | ||||||
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Check failure on line 94 in source/linux/Foundational_Components/Power_Management/pm_rtc_ddr.rst
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https://github.com/TexasInstruments/processor-sdk-doc/blob/master/CONTRIBUTING.md#indentation-and-whitespace