Dear Hao,


Thank you for the reply.

Am 12.09.20 um 10:10 schrieb Hao Wu:

Thanks for quick responses over this report.

Thank you for the quick follow-up.

quoted

Hao, I wouldn’t expect a longer timeout causing the TPM to be
queried less frequently, but I do not know the code well.

From our understanding, the TPM queries might be retried due to some
reason, increase timeout 3x would lower the query frequency to 1/3.
The explanation might be wrong, but the fact looks like the timeout
matters.  Unfortunately, engineers from Rubrik are not experts over
the TPM driver code neither :(

quoted

quoted

Be careful about making this a global change.  It could reduce
the TPM performance by 3x. We don't want to affect all TPMs to
fix a bug in an old TPM 1.2 chip from one vendor.

Linux has a no regression policy, so the performance penalty
wouldn’t matter. Unfortunately, the regression was only noticed
several years after being introduced in Linux v4.14-rc2.

So does that mean we are good to apply the global change ? Or we need
to discuss about the actual fix further?

To get a fix into the stable series, it first needs to be applied to the 
master branch. I guess you tested also with Linux master, right?

Please add the explanation from your email to Greg into the git commit 
message, format the patch with `git format-patch -1 -o outgoing` and 
send it with `git send-email outgoing/*` to the addresses listed for the 
subsystem in `MAINTAINERS` and the people listed in the commit 
introducing the regression.

Then it can be properly reviewed and discussed.


Kind regards,

Paul