Re: [PATCH v3 5/8] acpi: Enable TPM IRQ

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 17, 2020 at 07:59:51AM -0400, Stefan Berger wrote:
> On 6/17/20 4:22 AM, Auger Eric wrote:
> > Hi Stefan,
> > 
> > On 6/16/20 10:57 PM, Stefan Berger wrote:
> > > From: Stefan Berger <stefanb@linux.ibm.com>
> > > 
> > > Move the TPM TIS IRQ to unused IRQ 13, which is the only one accepted by
> > > Windows. Query for the TPM's irq number and enable the TPM IRQ unless
> > > TPM_IRQ_DISABLED is returned.
> > > 
> > > Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> > > CC: Michael S. Tsirkin <mst@redhat.com>
> > > ---
> > >   hw/i386/acpi-build.c  | 11 +++++------
> > >   include/hw/acpi/tpm.h |  2 +-
> > >   2 files changed, 6 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > > index 900f786d08..bb9a7f8497 100644
> > > --- a/hw/i386/acpi-build.c
> > > +++ b/hw/i386/acpi-build.c
> > > @@ -2021,6 +2021,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> > >               build_append_pci_bus_devices(scope, bus, pm->pcihp_bridge_en);
> > >               if (TPM_IS_TIS_ISA(tpm)) {
> > > +                int8_t irq = tpm_get_irqnum(tpm);
> > >                   if (misc->tpm_version == TPM_VERSION_2_0) {
> > >                       dev = aml_device("TPM");
> > >                       aml_append(dev, aml_name_decl("_HID",
> > > @@ -2035,12 +2036,10 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> > >                   crs = aml_resource_template();
> > >                   aml_append(crs, aml_memory32_fixed(TPM_TIS_ADDR_BASE,
> > >                              TPM_TIS_ADDR_SIZE, AML_READ_WRITE));
> > > -                /*
> > > -                    FIXME: TPM_TIS_IRQ=5 conflicts with PNP0C0F irqs,
> > > -                    Rewrite to take IRQ from TPM device model and
> > > -                    fix default IRQ value there to use some unused IRQ
> > > -                 */
> > > -                /* aml_append(crs, aml_irq_no_flags(TPM_TIS_IRQ)); */
> > > +
> > > +                if (irq != TPM_IRQ_DISABLED) {
> > Out of curiosity what is the goal to expose the irq num as a property
> > settable by the end-user if only 13 is known to work in all cases. At
> > least shouldn't we warn the end-user in case he attempts to change the
> > default value?
> 
> For Windows only IRQ 13 works (and I am not sure whether this has always
> been like this), Linux accepts several other ones. As for exposing it to the
> end-user, I may have taken this from soundblaster (sb16.c), which also
> exposes it. If someone plays around with the irq numbers I would say they
> must have some more Pc knowledge than  just trying random numbers.
> 
> 
>    Stefan

So is this useful to anyone? If no I'd say drop it.
I'm guessing sb16 has it since it is useful for running extremely old OSes which might
have weird quirks for a specific hardware.