Re: [PATCH 0/4] tpm: fix PS/2 devices not working on Braswell systems due CLKRUN enabled

From: Jason Gunthorpe
Date: Wed Dec 20 2017 - 12:44:11 EST

On Wed, Dec 20, 2017 at 05:45:16PM +0100, Javier Martinez Canillas wrote:

> CHP51 says "LPC Clock Control Using the LPC_CLKRUN# May Not Behave As Expected"
> and that the implication is that "The SoC may prevent a peripheral device from
> successfully requesting the LPC clock".

Now we are back to the beginning - the LPC_CLKRUN protocol is simply
broken in BSW chipsets, and it has nothing to do with the TPM?

Intel is trying to work around that broken-ness and still preserve
power management in the case where only the TPM is connected to the
LPC bus.. It is questionable to me if this is even a good idea, or if
Linux is the right place to implement this work around (eg something
in SMM mode may be more appropriate for a chipset bug)

I think your patch is still the right improvement, if the BIOS turned
the feature off, we should not turn it back on.