Re: question about setting TPM_CHIP_FLAG_IRQ in tpm_tis_core_init

[Jerry Snitselaar]

On Tue Nov 12 19, Stefan Berger wrote:
> On 11/11/19 10:36 PM, Jerry Snitselaar wrote:
> > Question about 1ea32c83c699 ("tpm_tis_core: Set TPM_CHIP_FLAG_IRQ 
> > before probing for interrupts").
> > Doesn't tpm_tis_send set this flag, and setting it here in 
> > tpm_tis_core_init short circuits what
> > tpm_tis_send was doing before? There is a bug report of an interrupt 
> > storm from a tpm on a t490s laptop
> > with the Fedora 31 kernel (5.3), and I'm wondering if this change 
> > could cause that. Before they got
> > the warning about interrupts not working, and using polling instead.
> I set this flag for the TIS because it wasn't set anywhere else. 
> tpm_tis_send() wouldn't set the flag but go via the path:
>
> if (!(chip->flags & TPM_CHIP_FLAG_IRQ) || priv->irq_tested)
>
>         return tpm_tis_send_main(chip, buf, len);
>
> the only other line for the TIS to set the IRQ flag was in the same 
> function further below, though that wouldn't be reached due to the 
> above:
>
> [...]
>
> priv->irq = irq;
>
> chip->flags |= TPM_CHIP_FLAG_IRQ;
>
>
>    Stefan

Ugh, you're right I was reading that as ! around both the flag and priv->irq_tested.

Should the flag be cleared if tpm_tis_probe_irq_single fails prior to calling
tpm_tis_gen_interrupt?