Re: [PATCH v1 4/5] fpga: dfl: add generic support for MSIX interrupts

[matthew . gerlach]

On Thu, 8 Sep 2022, Geert Uytterhoeven wrote:

> Hi Matthew,
>
> On Thu, Sep 8, 2022 at 7:34 PM <matthew.gerlach@xxxxxxxxxxxxxxx> wrote:
> > On Thu, 8 Sep 2022, Andy Shevchenko wrote:
> > > On Wed, Sep 07, 2022 at 02:37:32PM -0700, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> > > > On Tue, 6 Sep 2022, Andy Shevchenko wrote:
> > > > > On Tue, Sep 06, 2022 at 12:04:25PM -0700, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> > >
> > > ...
> > >
> > > > > > +  if (fid != FEATURE_ID_AFU && fid != PORT_FEATURE_ID_ERROR &&
> > > > > > +      fid != PORT_FEATURE_ID_UINT && fid != FME_FEATURE_ID_GLOBAL_ERR) {
> > > > > > +          v = readq(base);
> > > > > > +          v = FIELD_GET(DFH_VERSION, v);
> > > > > > +
> > > > > > +          if (v == 1) {
> > > > > > +                  v =  readq(base + DFHv1_CSR_SIZE_GRP);
> > > > >
> > > > > I am already lost what v keeps...
> > > > >
> > > > > Perhaps
> > > > >
> > > > >             v = readq(base);
> > > > >             switch (FIELD_GET(DFH_VERSION, v)) {
> > > > >             case 1:
> > > > >                     ...
> > > > >                     break;
> > > > >             }
> > > >
> > > > How about?
> > > >              if (FIELD_GET(DFH_VERSION, readq(base)) == 1) {
> > > >                      ...
> > > >              }
> > >
> > > This one tends to be expanded in the future, so I would keep it switch case.
> >
> > I'm okay with using the switch statement, but how about the following?
> >
> >                 switch (FIELD_GET(DFH_VERSION, readq(base))) {
> >                  case 1:
> >                         ...
> >                         break;
> >                 }
>
> Would it make sense to print an error if a newer version than 1 is detected?
> BTW, what is the expected value when DFHv1 is not detected? Zero
> or an arbitrary number?
>
> Gr{oetje,eeting}s,
>
>                        Geert

Hi Geert,

Currently, DFHs that are not version 1 should be version 0. I will fill in 
the switch statement to do nothing for version 0, and the default case 
will print a warning of an unexpected version.

Thanks for the feedback.

Matthew Gerlach
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                -- Linus Torvalds