[Nouveau] [PATCH 6/6] drm/nouveau: use MSI interrupts

[Lucas Stach]

Am Mittwoch, den 28.08.2013, 17:09 +1000 schrieb Ben Skeggs:
> On Wed, Aug 28, 2013 at 10:00 AM, Lucas Stach <dev at lynxeye.de> wrote:
> > MSIs were only problematic on some old, broken chipsets. But now that we
> > already see systems where PCI legacy interrupts are somewhat flaky, it's
> > really time to move to MSIs.
> >
> > Signed-off-by: Lucas Stach <dev at lynxeye.de>
> > ---
> >  drivers/gpu/drm/nouveau/core/include/subdev/mc.h |  1 +
> >  drivers/gpu/drm/nouveau/core/subdev/mc/base.c    | 17 +++++++++++++++++
> >  2 files changed, 18 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/nouveau/core/include/subdev/mc.h b/drivers/gpu/drm/nouveau/core/include/subdev/mc.h
> > index 9d2cd20..ce6569f 100644
> > --- a/drivers/gpu/drm/nouveau/core/include/subdev/mc.h
> > +++ b/drivers/gpu/drm/nouveau/core/include/subdev/mc.h
> > @@ -12,6 +12,7 @@ struct nouveau_mc_intr {
> >  struct nouveau_mc {
> >         struct nouveau_subdev base;
> >         const struct nouveau_mc_intr *intr_map;
> > +       bool use_msi;
> >  };
> >
> >  static inline struct nouveau_mc *
> > diff --git a/drivers/gpu/drm/nouveau/core/subdev/mc/base.c b/drivers/gpu/drm/nouveau/core/subdev/mc/base.c
> > index ec9cd6f..02b337e 100644
> > --- a/drivers/gpu/drm/nouveau/core/subdev/mc/base.c
> > +++ b/drivers/gpu/drm/nouveau/core/subdev/mc/base.c
> > @@ -23,6 +23,7 @@
> >   */
> >
> >  #include <subdev/mc.h>
> > +#include <core/option.h>
> >
> >  static irqreturn_t
> >  nouveau_mc_intr(int irq, void *arg)
> > @@ -43,6 +44,9 @@ nouveau_mc_intr(int irq, void *arg)
> >                 map++;
> >         }
> >
> > +       if (pmc->use_msi)
> > +               nv_wr08(pmc->base.base.parent, 0x00088068, 0xff);
> Register not present everywhere.
> 
> At the very least, the enabling of MSI should be disallowed on the
> earlier chipsets where it's not supported.  Though, it's perhaps
> possible that the pci_enable_msi() call will fail in all of these
> cases anyway.. I'm not certain.
> 
MSIs are required property for everything doing PCIe. So the only cases
where this should fail is plain PCI/AGP devices. I don't really have a
test system for those old cards set up.

But I remember Ilia having some legacy things plugged in, so maybe he
could test this patch and see how it goes?

> > +
> >         if (intr) {
> >                 nv_error(pmc, "unknown intr 0x%08x\n", stat);
> >         }
> > @@ -75,6 +79,8 @@ _nouveau_mc_dtor(struct nouveau_object *object)
> >         struct nouveau_device *device = nv_device(object);
> >         struct nouveau_mc *pmc = (void *)object;
> >         free_irq(device->pdev->irq, pmc);
> > +       if (pmc->use_msi)
> > +               pci_disable_msi(device->pdev);
> >         nouveau_subdev_destroy(&pmc->base);
> >  }
> >
> > @@ -96,6 +102,17 @@ nouveau_mc_create_(struct nouveau_object *parent, struct nouveau_object *engine,
> >
> >         pmc->intr_map = intr_map;
> >
> > +       pmc->use_msi = nouveau_boolopt(device->cfgopt, "NvMSI", true);
> > +       if (pmc->use_msi) {
> > +               ret = pci_enable_msi(device->pdev);
> > +               if (ret) {
> > +                       pmc->use_msi = false;
> > +               } else {
> > +                       nv_wr08(device, 0x00088068, 0xff);
> > +                       nv_info(pmc, "MSI interrupts enabled\n");
> > +               }
> > +       }
> > +
> >         ret = request_irq(device->pdev->irq, nouveau_mc_intr,
> >                           IRQF_SHARED, "nouveau", pmc);
> >         if (ret < 0)
> > --
> > 1.8.3.1
> >