Using a "voltage tolerance" for doing DVFS is not a proper way. It leads to a few issues: - voltage is limited to a narrow range near OPP voltage, so other consumers of the same regulator can't set their own constraints if they don't overlap with this narrow range. No ganged rails :( - usually OPP voltage is an absolute minimum voltage necessary for correct work (not taking into account AVS). Applying plus/minus tolerance can lead to an unstable device. For example omap-cpufreq has 4% tolerance configured, so for OMAP4430 MPU OPP50 we get 0.984V instead of 1.025V.
This series adds a new API to regulator FW to limit only minimum voltage. As example API is used for cpufreq-cpu0, but if it is accepted I'll fix other drivers (omap-cpufreq, imx6q-cpufreq, etc). Maybe regulator_set_voltage_tol() should be removed completely, because it started to be used in a wrong way. Patches are based on v3.9-rc7. I've tested them on v3.8 based branch on OMAP4430 Blaze board. Taras Kondratiuk (2): regulator: core: Add regulator_set_voltage_min() cpufreq: cpufreq-cpu0: Limit minimum voltage only drivers/cpufreq/cpufreq-cpu0.c | 12 ++++-------- include/linux/regulator/consumer.h | 6 ++++++ 2 files changed, 10 insertions(+), 8 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
