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SubjectRe: [PATCH v5 2/2] ACPI: amba bus probing support
From
On Mon, Jan 11, 2016 at 5:27 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Mon, Jan 11, 2016 at 05:13:20PM +0200, Andy Shevchenko wrote:
>> On Mon, Jan 11, 2016 at 3:26 PM, Aleksey Makarov
>> <aleksey.makarov@linaro.org> wrote:
>> > From: Graeme Gregory <graeme.gregory@linaro.org>

>> > +static int amba_handler_attach(struct acpi_device *adev,
>> > + const struct acpi_device_id *id)
>> > +{
>> > + struct amba_device *dev;
>> > + struct resource_entry *rentry;
>> > + struct list_head resource_list;
>> > + bool address_found = false;
>> > + int irq_no = 0;
>> > + int ret;
>> > +
>> > + /* If the ACPI node already has a physical device attached, skip it. */
>> > + if (adev->physical_node_count)
>> > + return 0;
>> > +
>> > + dev = amba_device_alloc(dev_name(&adev->dev), 0, 0);
>> > + if (!dev) {
>> > + dev_err(&adev->dev, "%s(): amba_device_alloc() failed\n",
>> > + __func__);
>> > + return -ENOMEM;
>> > + }
>> > +
>> > + INIT_LIST_HEAD(&resource_list);
>> > + ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
>> > + if (ret < 0)
>> > + goto err_free;
>> > +
>> > + list_for_each_entry(rentry, &resource_list, node) {
>> > + switch (resource_type(rentry->res)) {
>> > + case IORESOURCE_MEM:
>> > + if (!address_found) {
>> > + dev->res = *rentry->res;
>>
>> dev->res is 0 before this one, right? Could you use this fact instead
>> of address_found flag?
>
> amba_device_alloc() zero-initialises everything. However, dev->res is
> a struct resource, and I'd prefer _this_ method that the OT is using
> to testing some random part of struct resource.

So, you mean resource->start = 0 is not enough reliable?

>> > + default:
>> > + dev_warn(&adev->dev, "Invalid resource\n");
>>
>> Why? Isn't possible to have other resources for the devices?
>
> AMBA primecell devices have one memory region, and a number of
> interrupts. Other resource types don't make sense.

But isn't warning on the other side too noisy?

>> > + ret = amba_device_add(dev, &iomem_resource);
>> > + if (ret) {
>>
>> ret < 0?
>>
>> What to do if ret > 0? It will be considered as not error. Please,
>> check what function returns and adjust this.
>
> Non-zero is treated as an error by amba_device_add().

> Doing otherwise
> here puts it at odds to the outcome of that function. This code is fine.

Yes, and in this case ret > 0 should be converted to an appropriate
error code, otherwise ACPI core will consider this as a normal
execution, right?

--
With Best Regards,
Andy Shevchenko

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