Messages in this thread |  | | Subject | Re: [PATCH 1/5] tpm: add functions to set and unset the tpm chips reset state | From | Lino Sanfilippo <> | Date | Sun, 10 Apr 2022 11:03:01 +0200 |
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Hi,
On 07.04.22 at 16:25, Jason Gunthorpe wrote: > On Thu, Apr 07, 2022 at 01:18:45PM +0200, Lino Sanfilippo wrote: >> Currently it is not possible to set the tpm chips reset state from within >> the driver. This is problematic if the chip is still in reset after the >> system comes up. This may e.g. happen if the reset line is pulled into >> reset state by a pin configuration in the device tree. > > This kind of system is badly misdesigned. > > TPM PCRs fundementally cannot work if the TPM reset line is under > software control. > > Jason >
you may be right about the misdesign, but as a matter of fact there are systems which have the TPMs reset line connected to a GPIO and not the system reset. For those systems we should provide a way to let at least the driver put the TPM out of reset (note that on those systems the TPM reset can be triggered by software anyway by asserting/deasserting the GPIO line).
Regards, Lino
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