On Mon, Sep 28, 2020 at 05:52:43PM -0700, James Bottomley wrote: > I've got hold of an infineon TIS TPM which actually has a working > interrupt. I find even with the other fix I still need the patch below > to get the interrupt to fire because without it nothing ever sets > TPM_CHIP_FLAG_IRQ which means the interrupt test code is never > executed. > > Finally with all this probing fixed, I'm seeing interrupt storms. The > way this TPM seems to work is that if you allow it to send command > ready interrupts, it will send them any time it can accept a command. > The problem is if you clear the interrupt and it can accept a command, > it will send another command ready interrupt ... hence the storm since > the TPM is pretty much always in the command ready state. The only way > to mitigate this seems to be *only* to enable the command ready > interrupt when you're preparing to wait for the TPM to become ready. > i.e. these interrupts have to be treated as one shot enable, so the > interrupt routine has to mask the command ready interrupt before doing > a TPM_EOI in our way of doing things. There seems to be support for > this in the TIS spec around line 1135 where it advises us to keep all > interrupts masked until polling says we have to wait for a particular > state. > > James OK, this makes a lot of sense. I'll go through the patch set that you posted. Thank you. > > --- > > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index 6b884badabe7..1578d158416c 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -804,6 +810,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask, > return rc; > > priv->irq_tested = false; > + chip->flags |= TPM_CHIP_FLAG_IRQ; > > /* Generate an interrupt by having the core call through to > * tpm_tis_send > > /Jarkko
