Re: [PATCH] tpm: Make timeout logic simpler and more robust

From: Jarkko Sakkinen
Date: Tue Mar 12 2019 - 08:36:42 EST

On Mon, Mar 11, 2019 at 04:54:04PM -0700, Calvin Owens wrote:
> We're having lots of problems with TPM commands timing out, and we're
> seeing these problems across lots of different hardware (both v1/v2).
> I instrumented the driver to collect latency data, but I wasn't able to
> find any specific timeout to fix: it seems like many of them are too
> aggressive. So I tried replacing all the timeout logic with a single
> universal long timeout, and found that makes our TPMs 100% reliable.
> Given that this timeout logic is very complex, problematic, and appears
> to serve no real purpose, I propose simply deleting all of it.
> Signed-off-by: Calvin Owens <calvinowens@xxxxxx>

Have been thinking about this and I do agree. It has been like that
before my times with this subsystem so when I did the original TPM2
patches I carried this logic albeit even at that point I did not get it.
Now that I've been maintaining for over three years I'm confident that
this the Right Thing to do.