On Sat, Nov 17, 2012 at 11:11:59AM +0100, Rafael J. Wysocki wrote:
> > +static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
> > + void *data, void **return_value)
> > +{
> > + struct spi_master *master = data;
> > + struct resource_list_entry *rentry;
> > + struct list_head resource_list;
> > + struct acpi_device *adev;
> > + struct spi_device *spi;
> > + int ret;
> > +
> > + if (acpi_bus_get_device(handle, &adev))
> > + return AE_OK;
> > + if (acpi_bus_get_status(adev) || !adev->status.present)
> > + return AE_OK;
> > +
> > + spi = spi_alloc_device(master);
> > + if (!spi) {
> > + dev_err(&master->dev, "failed to allocate SPI device for %s\n",
> > + dev_name(&adev->dev));
> > + return AE_NO_MEMORY;
> > + }
> > +
> > + INIT_LIST_HEAD(&resource_list);
> > + ret = acpi_dev_get_resources(adev, &resource_list,
> > + acpi_spi_add_resource, spi);
> > + if (ret < 0)
> > + goto fail_put_dev;
> > +
> > + list_for_each_entry(rentry, &resource_list, node) {
> > + struct resource *r = &rentry->res;
> > +
> > + if (resource_type(r) == IORESOURCE_IRQ) {
> > + spi->irq = r->start;
> > + break;
> > + }
> > + }
> > +
> > + acpi_dev_free_resource_list(&resource_list);
>
> A potential problem is lurking here, or rather two of them.
>
> Suppose there are multiple IRQ resources for this device. The code
> above will cause GSIs to be registered for all of them, but we'll
> use only one eventually. Moreover, we'll use the last one, but
> perhaps we should use the first one instead?
Indeed we should use the first one.
> Maybe a better approach would be to make acpi_spi_add_resource()
> call acpi_dev_resource_interrupt(ares, 0, &r) directly and then skip all of
> the remaining IRQ resources if it finds one?
>
> For example set spi->irq to -1 initially, assign it if an IRQ
> resource is found and skip all of the remaining IRQ resources if
> it is non-negative?
OK, will do. Thanks.
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