Re: [PATCH v7 5/5] Driver: VMBus: Add Devicetree support

Saurabh Singh Sengar
2023-03-10T05:35:01Z

On Thu, Mar 09, 2023 at 09:16:25PM +0000, Wei Liu wrote:
> On Thu, Feb 23, 2023 at 03:29:05AM -0800, Saurabh Sengar wrote:
> [...]
> > +#ifdef CONFIG_ACPI
> > static int vmbus_acpi_add(struct platform_device *pdev)
> > {
> > acpi_status result;
> > @@ -2494,10 +2497,47 @@ static int vmbus_acpi_add(struct platform_device *pdev)
> > vmbus_mmio_remove();
> > return ret_val;
> > }
> > +#endif
> > +
> > +static int vmbus_device_add(struct platform_device *pdev)
> > +{
> > + struct resource **cur_res = &hyperv_mmio;
> > + struct of_range range;
> > + struct of_range_parser parser;
> > + struct device_node *np = pdev->dev.of_node;
> > + int ret;
> > +
> > + hv_dev = &pdev->dev;
> > +
> > + ret = of_range_parser_init(&parser, np);
> > + if (ret)
> > + return ret;
> > +
> > + for_each_of_range(&parser, &range) {
> > + struct resource *res;
> > +
> > + res = kzalloc(sizeof(*res), GFP_ATOMIC);
>
> Why GFP_ATOMIC here? I don't think this function will be called in
> atomic context, right?

Thanks for pointing this. I will fix this in next version.
Moreover, although there is a similar flag in the ACPI flow,
I am contemplating whether that also requires fixing.

>
> > + if (!res)
> > + return -ENOMEM;
> > +
> > + res->name = "hyperv mmio";
> > + res->flags = IORESOURCE_MEM | IORESOURCE_MEM_64;
>
> Are you sure IORESOURCE_MEM_64 is correct or required? The ACPI method
> does not set this flag.

Yes IORESOURCE_MEM_64 is required as there are cases where we are mapping
64 bit resources. But now I realize its better to fetch this info from range
struct only (range.flags), as for_each_of_range populates this flag.
I will fix this up as well.

>
> > + res->start = range.cpu_addr;
> > + res->end = range.cpu_addr + range.size;
> > +
> > + *cur_res = res;
> > + cur_res = &res->sibling;
> > + }
> > +
> > + return ret;
> > +}
> >
> > static int vmbus_platform_driver_probe(struct platform_device *pdev)
> > {
> > +#ifdef CONFIG_ACPI
> > return vmbus_acpi_add(pdev);
> > +#endif
>
> Please use #else here.
>
> > + return vmbus_device_add(pdev);
>
> Is there going to be a configuration that ACPI and OF are available at
> the same time? I don't see they are marked as mutually exclusive in the
> proposed KConfig.

Initially, the device tree functions was included in "#else" section after
the "#ifdef CONFIG_ACPI" section. However, it was subsequently removed to
increase the coverage for CI builds.

Ref: https://lkml.org/lkml/2023/2/7/910

Regards,
Saurabh

>
> Thanks,
> Wei.
>
> > }
> >
> > static int vmbus_platform_driver_remove(struct platform_device *pdev)
> > @@ -2643,12 +2683,24 @@ static int vmbus_bus_resume(struct device *dev)
> > #define vmbus_bus_resume NULL
> > #endif /* CONFIG_PM_SLEEP */
> >
> > +static const __maybe_unused struct of_device_id vmbus_of_match[] = {
> > + {
> > + .compatible = "microsoft,vmbus",
> > + },
> > + {
> > + /* sentinel */
> > + },
> > +};
> > +MODULE_DEVICE_TABLE(of, vmbus_of_match);
> > +
> > +#ifdef CONFIG_ACPI
> > static const struct acpi_device_id vmbus_acpi_device_ids[] = {
> > {"VMBUS", 0},
> > {"VMBus", 0},
> > {"", 0},
> > };
> > MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
> > +#endif
> >
> > /*
> > * Note: we must use the "no_irq" ops, otherwise hibernation can not work with
> > @@ -2677,6 +2729,7 @@ static struct platform_driver vmbus_platform_driver = {
> > .driver = {
> > .name = "vmbus",
> > .acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
> > + .of_match_table = of_match_ptr(vmbus_of_match),
> > .pm = &vmbus_bus_pm,
> > .probe_type = PROBE_FORCE_SYNCHRONOUS,
> > }
> > --
> > 2.34.1
> >