Re: [RFC] ARM: omap3: Enable HWMODS for HW Random Number Generator

From: Tony Lindgren
Date: Tue Oct 22 2019 - 12:06:50 EST


* Adam Ford <aford173@xxxxxxxxx> [191022 12:13]:
> On Mon, Sep 9, 2019 at 11:35 AM Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> >
> > * Pali RohÃr <pali.rohar@xxxxxxxxx> [190909 13:41]:
> > > On Monday 09 September 2019 08:37:09 Adam Ford wrote:
> > > > I applied this on 5.3 and it is working. I assume the same is true in for-next.
> >
> > Hmm I noticed I stopped getting RNG data after several rmmod modprobe
> > cycles, or several hd /dev/random reads. Anybody else seeing that?
> >
> > > > Do you want to submit a formal patch? I can mark it as 'tested-by'
> > > > This really helps speed up the startup sequence on boards with sshd
> > > > because it delays for nearly 80 seconds waiting for entropy without
> > > > the hwrng.
> > >
> > > Hi! When applying a patch, could you please disable this rng for n900?
> > >
> > > In omap3-n900.dts for rng should be status = "disabled" (as Tony already
> > > wrote), similarly like for aes.
> >
> > Yeah I'll post a proper patch after -rc1.
>
> Tony,
>
> I am just following up on this. Without the HWRNG there are some
> tools and daemons like sshd which wait a long time at startup. The
> patch you sent really helps speed up the startup time in these cases.
> At least in my case, it shaves 80 seconds off by eliminating the
> delays.
>
> Do you think you'll have time to post a more formal patch? If not, I
> can do it. I just don't know which mailing list is the more
> appropriate. I was able to verity your patch on a DM3730 and OMAP3530

Yeah sorry for the delays, I'll post it when I get a chance to
work on that again. I need to first deal with the other pending
patches for v5.5, and we've had quite a few fixes for v5.4.

Regards,

Tony