This patchset adds support for setting vdd core to 0.95V during suspend. I wanted to get some comments on the DT usage and also the location of the code, in sleep33xx.S. Since the am33xx PM code is not yet merged, the patchset is based on ti-linux-3.8.y kernel located at https://git.ti.com/ti-linux-kernel/ti-linux-kernel.
am33xx processors have a special VDD core operating point that can lower power consumption, but the operating point has many restrictions. One of the restrictions is that it does not support any DDR3 clock rates, meaning that the memory controller must be disabled to enter this operating point. For DDR2 systems, the clock rate must be changed, which can only be done from internal memory. For these reasons, the mode is most useful during suspend. The change must be done after the memory controller has been disabled. The memory controller is disabled as the last step in the suspend sequence, within sleep33xx.S. The patchset basically adds a small I2C controller to sleep33xx.S, allowing simple I2C messages to be sent to anything on the I2C1 bus. It can support any am33xx platform so long as VDD core can be controlled via simple writes on the I2C1 bus. Since am33xx is a device tree platform, I needed to find a way to integrate this into DT. I put the sleep and wake sequences as arrays of binary bytes in the I2C1 node. I'm not sure where else it would fit better, but I'm open to suggestions. An example sequence is included for Beaglebone, where this patchset has been tested. Russ Dill (2): ARM: OMAP2+: AM33XX: I2C Sleep/wake sequence support ARM: dts: add AM33XX vdd core opp50 suspend for Beaglebone. arch/arm/boot/dts/am335x-bone.dts | 25 +++++- arch/arm/mach-omap2/pm33xx.c | 108 ++++++++++++++++++++++ arch/arm/mach-omap2/pm33xx.h | 23 +++++ arch/arm/mach-omap2/sleep33xx.S | 184 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 339 insertions(+), 1 deletion(-) -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
