| Message ID | 20190321141010.19612-1-brgl@bgdev.pl (mailing list archive) |
|---|---|
| Headers | show |
| Series | ARM: da850: enable cpufreq in DT mode | expand |
On 3/21/19 9:10 AM, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > This series adds cpufreq-dt operating points for da850 boards supported > with device tree (da850-lcdk, da850-lego-ev3, da850-evm) and also > includes a fix for the da850-evm boardfile which checks an unset variable > to determine the highest available frequency for cpufreq. I can't find any old threads about this, but I recall that there was a problem with the USB OHCI controller breaking when switching frequencies. It didn't happen all of the time, but often enough that it made using cpufreq unusable for me. Is this still a problem? Also, a big-picture question. On boards with fixed regulators, what is the benefit of enabling frequency scaling? The power savings aspect seems negligible (< 1% in my tests) since the voltage cannot be changed.
czw., 21 mar 2019 o 16:29 David Lechner <david@lechnology.com> napisał(a): > > On 3/21/19 9:10 AM, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > This series adds cpufreq-dt operating points for da850 boards supported > > with device tree (da850-lcdk, da850-lego-ev3, da850-evm) and also > > includes a fix for the da850-evm boardfile which checks an unset variable > > to determine the highest available frequency for cpufreq. > > > I can't find any old threads about this, but I recall that there was a > problem with the USB OHCI controller breaking when switching frequencies. > It didn't happen all of the time, but often enough that it made using > cpufreq unusable for me. Is this still a problem? > Yes, it's still a problem, but it's bug-compatible with the legacy BSP from TI (project arago). I've spent some time trying to figure out the culprit at the time you were working on the clock driver, but eventually gave up. I think it's some kind of a HW issue. The controller would simple die after a couple transitions. Bart > Also, a big-picture question. On boards with fixed regulators, what is > the benefit of enabling frequency scaling? The power savings aspect > seems negligible (< 1% in my tests) since the voltage cannot be changed.
From: Bartosz Golaszewski <bgolaszewski@baylibre.com> This series adds cpufreq-dt operating points for da850 boards supported with device tree (da850-lcdk, da850-lego-ev3, da850-evm) and also includes a fix for the da850-evm boardfile which checks an unset variable to determine the highest available frequency for cpufreq. Last patch enables CPUFREQ_DT in davinci_all_defconfig. Bartosz Golaszewski (2): ARM: davinci: fix cpufreq registration on da850-evm ARM: dts: da850-evm: enable cpufreq David Lechner (2): ARM: dts: da850: add cpu node and operating points to DT ARM: davinci_all_defconfig: Enable CPUFREQ_DT arch/arm/boot/dts/da850-evm.dts | 30 +++++++++++++ arch/arm/boot/dts/da850-lcdk.dts | 31 ++++++++++++++ arch/arm/boot/dts/da850-lego-ev3.dts | 30 +++++++++++++ arch/arm/boot/dts/da850.dtsi | 56 +++++++++++++++++++++++++ arch/arm/configs/davinci_all_defconfig | 1 + arch/arm/mach-davinci/board-da850-evm.c | 12 +----- 6 files changed, 149 insertions(+), 11 deletions(-)