Am Mittwoch, den 28.08.2013, 17:09 +1000 schrieb Ben Skeggs:
> On Wed, Aug 28, 2013 at 10:00 AM, Lucas Stach <dev@xxxxxxxxxx> 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@xxxxxxxxxx>
> > ---
> > 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
> >
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