[PATCH v2 6/7] drm/panfrost: Add support for GPU heap allocations

[Rob Herring]

On Thu, Jul 25, 2019 at 7:08 AM Robin Murphy <robin.murphy at arm.com> wrote:
>
> Hi Rob,
>
> On 25/07/2019 02:10, Rob Herring wrote:
> [...]
> > @@ -328,6 +427,18 @@ static irqreturn_t panfrost_mmu_irq_handler(int irq, void *data)
> >               access_type = (fault_status >> 8) & 0x3;
> >               source_id = (fault_status >> 16);
> >
> > +             /* Page fault only */
> > +             if ((status & mask) == BIT(i)) {
> > +                     WARN_ON(exception_type < 0xC1 || exception_type > 0xC4);
> > +
> > +                     ret = panfrost_mmu_map_fault_addr(pfdev, i, addr);
> > +                     if (!ret) {
> > +                             mmu_write(pfdev, MMU_INT_CLEAR, BIT(i));
> > +                             status &= ~mask;
> > +                             continue;
> > +                     }
> > +             }
> > +
> >               /* terminal fault, print info about the fault */
> >               dev_err(pfdev->dev,
> >                       "Unhandled Page fault in AS%d at VA 0x%016llX\n"
> > @@ -368,8 +479,9 @@ int panfrost_mmu_init(struct panfrost_device *pfdev)
> >       if (irq <= 0)
> >               return -ENODEV;
> >
> > -     err = devm_request_irq(pfdev->dev, irq, panfrost_mmu_irq_handler,
> > -                            IRQF_SHARED, "mmu", pfdev);
> > +     err = devm_request_threaded_irq(pfdev->dev, irq, NULL,
> > +                                     panfrost_mmu_irq_handler,
> > +                                     IRQF_ONESHOT, "mmu", pfdev);
>
> The change of flags here breaks platforms using a single shared
> interrupt line.

Do they exist? I think this was largely copy-n-paste leftover from the
lima driver where utgard has a bunch of irqs and so they get combined.
While it's possible certainly, I'd like to avoid having to do further
rework either to use a workqueue or we need a single driver handler
which then dispatches the sub handlers. The problem is threaded irq
handlers don't work with shared irqs.

Rob