Re: [PATCH] tpm/tpm_tis: Fix variable reset during IRQ probing

[Tianjia Zhang]

On 1/15/21 5:23 PM, Jarkko Sakkinen wrote:
> On Thu, Jan 14, 2021 at 12:12:16PM +0800, Tianjia Zhang wrote:
> > On 1/14/21 10:51 AM, Jarkko Sakkinen wrote:
> > > On Wed, Jan 13, 2021 at 08:00:21PM +0800, Tianjia Zhang wrote:
> > > > In tpm_tis_core_init(), tpm2_probe() will be called first, this
> > > > function will eventually call tpm_tis_send(), and then
> > > > tpm_tis_probe_irq_single() will detect whether the interrupt is
> > > > normal, mainly the installation interrupted, set `priv->irq_tested`
> > > > to false. The logic will eventually be executed to tpm_tis_send()
> > > > to trigger an interrupt.
> > > >
> > > > There is currently such a scenario, which will cause the IRQ probe
> > > > code to never be executed, so that the TPM device is in polling
> > > > mode: after setting irq_tested to false, an interrupt occurs
> > > > between entering the ttpm_tis_send() function, and the interrupt
> > > > will be first set irq_tested to true will cause the IRQ probe code
> > > > to never be executed.
> > >
> > > Can you describe the scenario more detail?
> >
> > The problematic scenario we encountered is like this. The following figure
> > shows the execution flow of tpm_tis_core_init(). An interrupt occurred
> > before the IRQ probe. This interrupt was caused by tpm2_probe(), but it was
> > triggered before the IRQ probe was executed, and the interrupt handler would
> > set irq_tested to true, so the IRQ probe code can never execute, that is,
> > the code marked 2 in the figure will never happen.
>
> TPM_INT_ENABLE is cleared on reset [*].
>
> [*] Section 5.9.1
>      https://trustedcomputinggroup.org/resource/pc-client-work-group-pc-client-specific-tpm-interface-specification-tis/
>
> /Jarkko

Hi,

I got it, this seems to be a firmware issue. Thanks for your reply.

Best regards,
Tianjia