Re: [PATCH] Fix Atmel TPM crash caused by too frequent queries

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Mon, Sep 28, 2020 at 01:27:14PM -0700, Hao Wu wrote:
> 
> 
> > On Sep 28, 2020, at 12:47 PM, Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:
> > 
> > On Mon, Sep 28, 2020 at 10:49:56AM -0700, Hao Wu wrote:
> >> Hi Jarkko,
> >> 
> >> https://github.com/torvalds/linux/commit/9f3fc7bcddcb51234e23494531f93ab60475e1c3 
> >> Is the one introducing the issue since 4.14. Then the other three commits
> >> changed the relevant code a bit. Probably you can check the timestamp / release version
> >> on each commit to understand the relationship.
> >> 
> >> I think the original patch commit message can help you understand the root cause.
> >> Attaching the commit here for your convenience.
> >> 
> >> Thanks
> >> Hao
> > 
> > Please, again, when you respond quote properly instead of putting your
> > response on top. Thank you.
> > 
> > Yes, I know the issue and it is already documented also in the James'
> > earlier patch that did a similar change. I.e. for some reason some TPM's
> > (or the bus itself) do not like poking it too often.
> Yes, probably. Although the issue James’s patch fixes has the same error code,
> it is about a different issue which is similar.

OK, great.

> > So: what if you revert on using msleep(TPM_TIMEOUT) in
> > wait_for_tpm_stat(), i.e. revert to the behaviour before the
> > aformentioned commit?
> I believe that should resolve the issue as well

I'd return to the old code that works instead of doing something new
along the lines. James?

Anyway, thanks a lot for coming with this. I think we are making at
least some progress sorting this out.

Also want to underline that my comments about quoting emails did not
have anything to do that I would not appreciate this feedback. It is
just a "protocol thing".

> Thanks
> Hao

/Jarkko