On Mon 11 Jan 15:48 CST 2021, Doug Anderson wrote: > Hi Bjorn, > > On Mon, Dec 7, 2020 at 2:33 PM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote: > > > > For a bunch of rails we really don't do anything with them in Linux. > > These are things like modem voltage rails that the modem manages these > > itself and core rails (like IO rails) that are setup to just > > automagically do the right thing by the firmware. > > > > Let's stop even listing those rails in our device tree. > > > > The net result of this is that some of these rails might be able to go > > down to a lower voltage or perhaps transition to LPM (low power mode) > > sometimes. > > > > Here's a list of what we're doing and why: > > > > * L1A - only goes to SoC and doesn't seem associated with any > > particular peripheral. Kernel isn't doing anything with > > this. Removing from dts. NET IMPACT: rail might drop from 1.2V to > > 1.178V and switch to LPM in some cases depending on firmware. > > * L2A - only goes to SoC and doesn't seem associated with any > > particular peripheral. Kernel isn't doing anything with > > this. Removing from dts. NET IMPACT: rail might switch to LPM in > > some cases depending on firmware. > > * L3A - only goes to SoC and doesn't seem associated with any > > particular peripheral. Kernel isn't doing anything with > > this. Removing from dts. NET IMPACT: rail might switch to LPM in > > some cases depending on firmware. > > * L5A - seems to be totally unused as far as I can tell and doesn't > > even come off QSIP. Removing from dts. > > * L6A - only goes to SoC and doesn't seem associated with any > > particular peripheral (I think?). Kernel isn't doing anything with > > this. Removing from dts. NET IMPACT: rail might switch to LPM in > > some cases depending on firmware. > > * L16A - Looks like this is only used for internal RF stuff. Removing > > from dts. NET IMPACT: rail might switch to LPM in some cases > > depending on firmware. > > * L1C - Just goes to WiFi / Bluetooth. Trust how IDP has this set and > > put this back at 1.616V min. > > * L4C - This goes out to the eSIM among other places. This looks like > > it's intended to be for SIM card and modem manages. NET IMPACT: > > rail might switch to LPM in some cases depending on firmware. > > * L5C - This goes to the physical SIM. This looks like it's intended > > to be for SIM card and modem manages. NET IMPACT: rail might drop > > from 1.8V to 1.648V and switch to LPM in some cases depending on > > firmware. > > > > NOTE: in general for anything which is supposed to be managed by Linux > > I still left it all forced to HPM since I'm not 100% sure that all the > > needed calls to regulator_set_load() are in place and HPM is safer. > > Switching more things to LPM can happen in a future patch. > > > > ALSO NOTE: Power measurements showed no measurable difference after > > applying this patch, so perhaps it should be viewed more as a cleanup > > than any power savings. > > > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > > --- > > > > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 82 ++------------------ > > 1 file changed, 7 insertions(+), 75 deletions(-) > > We've been running with this in the downstream tree since December 8th > and nobody has yelled. You can see <https://crrev.com/c/2573506>. Is > it a good time for it to land upstream? > Sure thing, I will pick it up. Thanks for the ping! Regards, Bjorn
