On Tue, 19 Mar 2024 at 20:15, Caleb Connolly <caleb.conno...@linaro.org> wrote: > > Hi Sumit, > > On 19/03/2024 13:49, Sumit Garg wrote: > > Hi Caleb, > > > > On Tue, 19 Mar 2024 at 17:52, Caleb Connolly <caleb.conno...@linaro.org> > > wrote: > >> > >> We don't support USB super-speed in U-Boot yet, we lack the SS PHY > >> drivers, however from my testing even with a PHY driver there seem to be > >> other issues when talking to super-speed peripherals. > >> > >> In pursuit of maintaining upstream DT compatibility, > > > > I can understand the reasoning behind this but since we enable these > > fixups for every Qcom platform it may turn out to be counter > > productive. There can be embedded use-cases where bootup times have > > stringent requirements. Also, depending upon CPU speed/freq the add-on > > times due to these can be significant. > > I have measured this on a few different boards: > > On DB410c, the slowest board we currently support > * of_live_build took 7228us > * Fixing up USB nodes took 131us > * Fixing up power domains took 88us > > On RB1 (the slowest new platform with a QCM2290 SoC) > * of_live_build took 2078us > * Fixing up USB nodes took 39us > * Fixing up power domains took 27us > > The time taken initially to build the livetree is likely made back as it > is much much faster to query than the flat tree (as you can see, walking > every single node takes <100us on db410c). I took some rough > measurements of the boot-to-console time on sdm845 (see the "enable > livetree" patch) and basically concluded that the delta between live and > flat trees is within the margin of error. > > If a specific board for whatever reason wants to avoid using OF_LIVE > then I'm fine with that, db410c isn't using it for example.
Okay that's fair. Let's try this approach and see if it pans out well. -Sumit
