Re: [PATCH v3 16/17] driver/edac: enable Hygon support to AMD64 EDAC driver

[Pu Wen]

On 2018/8/12 3:56, Michael Jin wrote:
> On Sat, Aug 11, 2018 at 9:30 AM, Pu Wen <puwen@xxxxxxxx> wrote:
> > diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
> > index 18aeabb..fb81354 100644
> > --- a/drivers/edac/amd64_edac.c
> > +++ b/drivers/edac/amd64_edac.c
> > @@ -211,7 +211,7 @@ static int __set_scrub_rate(struct amd64_pvt *pvt, u32 new_bw, u32 min_rate)
> >
> >          scrubval = scrubrates[i].scrubval;
> >
> > -       if (pvt->fam == 0x17) {
> > +       if (pvt->fam == 0x17 || pvt->vendor == X86_VENDOR_HYGON) {
> >                  __f17h_set_scrubval(pvt, scrubval);
>
> Separating the vendor check as an "else if (pvt->vendor ==
> X86_VENDOR_HYGON)" block would make architectural changes (future
> hygon models, i.e. 19h, 20h, etc) less confusing.

Your suggestion is reasonable, but that might make the branch a little
complicated.If we explicitly testing Hygon family in condition case,
will that be ok?
+    if (pvt->fam == 0x17 ||
+       (pvt->vendor == X86_VENDOR_HYGON && pvt->fam == 0x18))

> > +                       amd64_read_pci_cfg(pvt->F6,
> > +                               F17H_SCR_BASE_ADDR, &scrubval);
> > +                       if (scrubval & BIT(0)) {
> > +                               amd64_read_pci_cfg(pvt->F6,
>
> The new lines after "amd64_read_pci_cfg(pvt->F6," can be removed.

To fix the warning "line over 80 characters" reported by running the
checking script checkpatch.pl, I added the new line.
But your sugesstion is reasonable, remove the new line will make the
codes much easier to read.

> > @@ -1051,6 +1065,16 @@ static void determine_memory_type(struct amd64_pvt *pvt)
> >                  else
> >                          pvt->dram_type = MEM_DDR4;
> >                  return;
> > +       case 0x18:
> > +               if (pvt->vendor == X86_VENDOR_HYGON) {
>
> This vendor checking is not necessary as there are no other known
> family 18h processors.
>
>
> >          switch (pvt->fam) {
> > @@ -3192,6 +3227,13 @@ static struct amd64_family_type *per_family_init(struct amd64_pvt *pvt)
> >                  pvt->ops        = &family_types[F17_CPUS].ops;
> >                  break;
> >
> > +       case 0x18:
> > +               if (pvt->vendor == X86_VENDOR_HYGON) {
> > +                       fam_type        = &family_types[HYGON_F18_CPUS];
> > +                       pvt->ops        = &family_types[HYGON_F18_CPUS].ops;
> > +                       break;
> > +               }
>
> There is a missing second 'break' statement after the "if (pvt->vendor
> == X86_VENDOR_HYGON)" block for case 0x18, see case 0x15 and case 0x16
> for comparison.

The missed second 'break' is on purpose. Thinking that if BIOS report
a vendor AMD and family 18h processor(which is not in case now),
the code will fall through and print out "Unsupported family".

> > diff --git a/drivers/edac/mce_amd.c b/drivers/edac/mce_amd.c
> > index 2ab4d61..f7adc47 100644
> > +       case 0x18:
> > +               if (c->x86_vendor == X86_VENDOR_HYGON) {
> > +                       xec_mask = 0x3f;
> > +                       if (!boot_cpu_has(X86_FEATURE_SMCA)) {
> > +                               pr_warn("Decoding supported only on Scalable MCA processors.\n");
> > +                               goto err_out;
> > +                       }
> > +                       break;
> > +               }
>
> The 'break' statement could be moved outside of the "if (c->x86_vendor
> == X86_VENDOR_HYGON)" block, this is to allow case 0x18 to reach the
> 'break' statement if the vendor is not X86_VENDOR_HYGON.

For the same reason as previous, if the vendor is not X86_VENDOR_HYGON,
it's not a valid vendor by now, and should fall through to the default
case and print out error message.

Thanks,
Pu Wen