linux-kernel - Re: [tpmdd-devel] [PATCH] tpm, tpm_crb: remove redundant CRB_FL_CRB

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Message-ID: <20161019160928.n5fswy25t2ppdh73@intel.com>
Date:   Wed, 19 Oct 2016 19:09:28 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [tpmdd-devel] [PATCH] tpm, tpm_crb: remove redundant
 CRB_FL_CRB_START flag

On Wed, Oct 19, 2016 at 10:28:29AM +0000, Winkler, Tomas wrote:
> 
> 
> > 
> > On Mon, Oct 17, 2016 at 11:42:24PM +0300, Jarkko Sakkinen wrote:
> > > Because all the existing hardware have HID MSFT0101 we end up always
> > > setting CRB_FL_CRB_START flag as a workaround for 4th Gen Core CPUs.
> > > Even if ACPI start is used, the driver will always issue also CRB start.
> 
> Do you have some more historical data about this fix, I was wondering
> about this quirk before, when restructuring the start method parsing.
> The description is ' in practice seems to require both'  sounds not
> certain about the root cause of this.

I have a 4th Gen Core NUC where I experienced this issue. It reported
requiring only ACPI start but actually required ACPI + CRB start. The
comment could have been better.

/Jarkko