Re: [RFC][PATCH 0/9] tpm: fix driver so that burstcount can be safely ignored

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Alexander Steffen <Alexander.Steffen@infineon.com>
Cc: nayna@linux.vnet.ibm.com, kgold@linux.vnet.ibm.com,
	linux-integrity@vger.kernel.org
Subject: Re: [RFC][PATCH 0/9] tpm: fix driver so that burstcount can be safely ignored
Date: Sun, 24 Dec 2017 22:41:09 +0200	[thread overview]
Message-ID: <20171224204109.fobx53ffmog2a5nk@linux.intel.com> (raw)
In-Reply-To: <20171215120439.v7fvyy2cuauhnl2h@linux.intel.com>

On Fri, Dec 15, 2017 at 02:04:39PM +0200, Jarkko Sakkinen wrote:
> On Fri, Dec 08, 2017 at 07:46:49PM +0100, Alexander Steffen wrote:
> > Disclaimer: This is RFC because unfortunately I do not have the time to bring it up to the usual standards. But from lying around on my hard disk it definitely won't improve, so I've decided to publish it now, to get at least some feedback or maybe for somebody else to pick it up. Since the work began some time ago, it is probably not rebased against the current state (but hopefully still applies).
> > 
> > This is a collection of all the fixes I made during the investigation of the problems with the "ignore burstcount" change. These are mainly fixes for the wait state handling in tpm_tis_spi, that probably was not really tested so far, since the previous implementation avoided wait states as far as possible. It also includes changes to tpm_tis_core, so that it follows the specification more closely. Finally, I've included a rebased version of the original "ignore burstcount" patch. Together, those patches pass all my tests and also each intermediate step is fine (so that bisecting still works).
> > 
> > Alexander Steffen (8):
> >   tpm_tis_core: clean up whitespace
> >   tpm_tis_core: access single TIS registers before doing complex
> >     transfers
> >   tpm_tis_core: correctly wait for flags to become zero
> >   tpm_tis_core: send all data in single operation
> >   tpm_tis_core: use XDATA_FIFO for transfers if available
> >   tpm_tis_spi: fix sending wrong data during wait state handling
> >   tpm_tis_spi: release CS line when wait state handling fails
> >   tpm_tis_spi: add delay between wait state retries
> > 
> > Nayna Jain (1):
> >   tpm: ignore burstcount to improve tpm_tis send() performance
> > 
> >  drivers/char/tpm/tpm_tis_core.c | 131 ++++++++++++++++++++--------------------
> >  drivers/char/tpm/tpm_tis_core.h |  26 ++++----
> >  drivers/char/tpm/tpm_tis_spi.c  |  21 +++++--
> >  3 files changed, 95 insertions(+), 83 deletions(-)
> > 
> > -- 
> > 2.7.4
> > 
> 
> Might not have time to review this before holidays but will do if
> I can.

Unfortunately this and your patches for broken TPMs came so late that
they have no chance to make into 4.16. Thus, I will postpone their
review after the pull request and take care of the high priority stuff
for that release.

/Jarkko