From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Wilson Subject: Re: Regarding recently Added TPM2.0 support to the Nuvoton i2c driver Date: Wed, 27 Jul 2016 16:46:55 -0500 Message-ID: <20160727214655.GA16318@us.ibm.com> References: <5797A893.9020205@linux.vnet.ibm.com> <20160726201711.GA17742@obsidianresearch.com> <20160726203902.GA17730@us.ibm.com> <20160726210344.GA18332@obsidianresearch.com> <20160727160511.GA26597@us.ibm.com> <20160727163152.GA27915@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20160727163152.GA27915-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Jason Gunthorpe Cc: Andrew Azmansky , David Heller , tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net On Wed, Jul 27, 2016 at 10:31:52AM -0600, Jason Gunthorpe wrote: > On Wed, Jul 27, 2016 at 11:05:14AM -0500, George Wilson wrote: > > > > Yes, generally Linux expects DT to be set correctly by the boot > > > firmware. Early firmware needs to know the TPM type anyhow to do the > > > TPM setup, so this doesn't seem like a realistic scenario. > > > > A reset is required after upgrade/downgrade. But the version still > > needs to be detected by the firmware somehow. It could be configured > > manually in firmware state after the upgrade/downgrade to properly set > > the property, which seems much less desirable than a probe. > > Well, the firmware has to take care of this. If the firmware wants to > support switchable firmware it needs to be able to do probe that works > with all the firmware versions. > > ACPI and DT both expect the TPM version to be passed to the OS, it is > up to the firmware to do that correctly.. > > The fact you've already seen TPM2 probing failures makes me very > reluctant to turn it on more broadly, and maybe even think we should > get rid of it from tis too.. Cool, that clarifies it precisely: the expectation is that firmware will do any necessary probing and pass the property up in the device tree. All drivers supporting OF must use the data property as a flag for 2.0 for models capable of 2.0 function. > > Jason > -- George Wilson IBM Linux Technology Center Security Development ------------------------------------------------------------------------------