On Tue, Dec 19, 2017 at 12:34:46AM +0100, Javier Martinez Canillas wrote: > Hello Jason, > > On 12/18/2017 09:19 PM, Jason Gunthorpe wrote: > > On Mon, Dec 18, 2017 at 07:34:29PM +0000, Shaikh, Azhar wrote: > > > >>> IIUC, if CLKRUN_EN is enabled, then all the devices attached to the > >>> LPC bus have to support the CLKRUN protocol. My guess is that on > >>> some Braswell systems LPC power management is enabled but the TPM > >>> device doesn't have CLKRUN support. > >> > >> I think this is what might be happening here. > > > > That makes it a BIOS bug, not a chipset bug, and we shouldn't be > > trying to fix it like this in Linux. > > > > Indeed, the system integrator should make sure that all peripherals that > are connected through the LPC bus either support the CLKRUN protocol and > CLKRUN_EN is enabled or CLKRUN_EN should be disabled. I would like to hear from Intel why they made this patch in the first place, since we are mostly guessing... > 1) Leave the code as is and apply the patch I shared with James. In that > case the CLKRUN protocol will be disabled only during TPM transactions > and not enabled again after transactions if it wasn't enabled. This seems necessary no matter what, especially if it works.. > 2) Drop the pending CLKRUN patch in linux-tpmdd and revert CLKRUN commit > in mainline. And instead of disabling the CLKRUN protocol during the > TPM transactions, disable if the CLKRUN_EN is enabled and the system > is in a list of systems that have a TPM that doesn't support CLKRUN. This is also a good possible idea. Again, depends why Intel did this. I assumed it was a chipset bug since Intel was sending it not a system builder.. Jason
