Re: [PATCH 0/5] AM437x: Add rtc-only + DDR mode support

[keerthy <j-keerthy@ti.com>]

On 3/23/2019 12:02 AM, Russell King - ARM Linux admin wrote:
> On Fri, Mar 22, 2019 at 10:46:14PM +0530, Keerthy wrote:
>> RTC plus DDR in self-refresh is power a saving mode where in the entire
>                                   "a power" ?

Will correct the above typo.

> 
>> system including the different voltage rails from PMIC are shutdown except
>> the ones feeding on to RTC and DDR. DDR is kept in self-refresh hence the

As explained above All the voltage rails of PMIC are shut off except for 
RTC and DDR Rails.

>> contents are preserved. RTC ALARM2 is connected to PMIC_EN line once
>> we the ALARM2 is triggered we enter the mode with DDR in self-refresh
> 
> Doesn't make sense.
> 
>> and RTC Ticking. After a predetermined time an RTC ALARM1 triggers waking
>> up the system.
> 
> Huh, you start off explaining the wiring above... how does RTC ALARM1
> trigger waking up the system if RTC ALARM2 is connected to the PMIC
> and all other power is shut down?
The entire PMIC is shutdown but for RTC rail. RTC is a separate voltage 
domain and is powered up during this power save mode.

http://www.ti.com/lit/ug/spruhl7h/spruhl7h.pdf Page 2884.

> 
>> The control goes to bootloader. The bootloader then checks
>> RTC scratchpad registers to confirm it was an rtc_only wakeup and follows
>> a different path, configure bare minimal clocks for ddr and then jumps to
>> the resume address in another RTC scratchpad registers and transfers the
>> control to Kernel. Kernel then restores the saved context.
>>
>> The patch series adds rtc-only + DDR mode support am am437x
>> Tested DS0, rtc+ddr back and forth on am437x-gp-evm board.
>>
>> This mode works only with u-boot built with am43xx_evm_rtconly_defconfig
>>
>> Additional patch is needed for omap-gpio save restore which will
>> come as fixes later.
>>
>> Keerthy (5):
>>    rtc: OMAP: Add support for rtc-only mode
>>    rtc: interface: Add power_off_program to rtc_class_ops
>>    arm: mach-omap2: pm33xx: Add support for rtc+ddr in self refresh mode
>>    soc: ti: pm33xx: Push the am33xx_push_sram_idle to the top
>>    soc: ti: pm33xx: AM437X: Add rtc_only with ddr in self-refresh support
>>
>>   arch/arm/mach-omap2/pm33xx-core.c    |  76 +++++++-
>>   drivers/rtc/interface.c              |  12 ++
>>   drivers/rtc/rtc-omap.c               |  49 ++++-
>>   drivers/soc/ti/Kconfig               |   5 +-
>>   drivers/soc/ti/pm33xx.c              | 272 ++++++++++++++++++++++-----
>>   include/linux/platform_data/pm33xx.h |   5 +
>>   include/linux/rtc.h                  |   2 +
>>   7 files changed, 360 insertions(+), 61 deletions(-)
>>
>> -- 
>> 2.17.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>