From: Mike Turquette <mturquette@xxxxxxxxxx> This series creates a new callback for struct voltagedomain, .get_voltage. This fetches the voltage from hardware, if possible, and returns it to the caller. We use this call to populate voltdm->nominal_volt at boot time. The need for this came out of the Adaptive Body-Bias patches. There is a corner case where voltdm->nominal_volt is zero at boot, but the ABB pre-scale function needs to know the current voltage as a part of its logic. Without this series voltdm->nominal_volt will be zero until after voltdm->scale completes, which is too late for the ABB pre-scale logic. It is possible to have ABB without this series. In the event that voltdm->nominal_volt is zero then the ABB pre-scale function can simply return early. However this opens up a condition that burns power needlessly: 1) The bootloader enables Forward Body-Bias mode on the ABB ldo and runs the voltage domain at a high OPP 2) Linux boots and the first transition of that voltage domain is to a lower OPP. 3) The voltage of that vdd is unknown so the ABB pre-scale function returns early and FBB is left enabled at an OPP that would otherwise not need it. This scenario is not validated and is best avoided. This series is one step towards that. Mike Turquette (5): ARM: omap: vc: replace data_shift with data_mask ARM: omap: introduce .get_voltage callback ARM: omap: vc: .get_voltage callback ARM: omap: vp: .get_voltage callback ARM: omap: initialize voltdm->nominal_volt arch/arm/mach-omap2/vc.c | 23 ++++++++++++++++++++++- arch/arm/mach-omap2/vc.h | 3 ++- arch/arm/mach-omap2/vc3xxx_data.c | 2 +- arch/arm/mach-omap2/vc44xx_data.c | 2 +- arch/arm/mach-omap2/voltage.c | 13 +++++++++++++ arch/arm/mach-omap2/voltage.h | 1 + arch/arm/mach-omap2/vp.c | 22 ++++++++++++++++++++++ arch/arm/mach-omap2/vp.h | 1 + 8 files changed, 63 insertions(+), 4 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
