Re: [PATCH v3 3/4] tpm: Allow TPM chip drivers to override reported command durations

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Tue, Jun 07, 2016 at 11:32:35AM -0600, Jason Gunthorpe wrote:
> On Tue, Jun 07, 2016 at 07:25:24AM -0700, Ed Swierk wrote:
> > I followed the example of the existing update_timeouts callback, which
> > is also used only by tpm_tis.
> 
> The callback is because only TIS has the did_vid stuff which is needed
> to key the adjustment. Other interfaces do not have that information.
> 
> This was an ugly historical mistake:
> 
> > >> -     /* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
> > >> -      * value wrong and apparently reports msecs rather than usecs. So we
> > >> -      * fix up the resulting too-small TPM_SHORT value to make things work.
> > >> -      * We also scale the TPM_MEDIUM and -_LONG values by 1000.
> > >> -      */
> > >> -     if (chip->vendor.duration[TPM_SHORT] < (HZ / 100)) {
> > >> -             chip->vendor.duration[TPM_SHORT] = HZ;
> > >> -             chip->vendor.duration[TPM_MEDIUM] *= 1000;
> > >> -             chip->vendor.duration[TPM_LONG] *= 1000;
> > >> -             chip->vendor.duration_adjusted = true;
> 
> It should have been did/vid key'd as well, not heuristic.
> 
> Can the existing update_timeouts be broadened to do both adjustments,
> or do they really need to be at different times?

This would be a better idea.

> Jason

/Jarkko

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