linux-kernel - Re: [BISECTED] tpm CLKRUN breaks PS/2 keyboard and touchpad on Braswell system

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Date:   Mon, 18 Dec 2017 13:17:50 -0700
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Ettle <james@...le.org.uk>,
        linux-integrity@...r.kernel.org, azhar.shaikh@...el.com,
        linux-kernel@...r.kernel.org, james.l.morris@...cle.com
Subject: Re: [BISECTED] tpm CLKRUN breaks PS/2 keyboard and touchpad on
 Braswell system

On Mon, Dec 18, 2017 at 08:29:30PM +0100, Javier Martinez Canillas wrote:

> My knowledge of LPC is near to non-existent so I please forgive me if I'm wrong,
> but my understanding is that it's the opposite of what you said.
> 
> When CLKRUN_EN is SET, power management is ENABLED on the LPC bus and the host
> LCLK clock may be stopped when entering in some low-power states.
>
> The CLKRUN# signal is then used by peripherals to restart the LCLK clock after
> resuming from low-power states to be able to transmit again.
> 
> When CLKRUN_EN is CLEAR, power management is DISABLED on the LPC bus and the
> host LCLK clock is never stopped even when entering in some low-power states.

Okay, that makes sense.

Jason