linux-kernel - Re: [PATCH v17 08/10] ACPI / scan: do not enumerate Indirect IO host children

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Message-ID: <2309217.pWfZsU88YQ@aspire.rjw.lan>
Date:   Mon, 19 Mar 2018 11:30:11 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     John Garry <john.garry@...wei.com>
Cc:     mika.westerberg@...ux.intel.com, rafael@...nel.org,
        lorenzo.pieralisi@....com, hanjun.guo@...aro.org,
        robh+dt@...nel.org, bhelgaas@...gle.com, arnd@...db.de,
        mark.rutland@....com, olof@...om.net, dann.frazier@...onical.com,
        andy.shevchenko@...il.com, robh@...nel.org,
        andriy.shevchenko@...ux.intel.com, joe@...ches.com,
        benh@...nel.crashing.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linuxarm@...wei.com, minyard@....org, devicetree@...r.kernel.org,
        linux-arch@...r.kernel.org, rdunlap@...radead.org,
        gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
        frowand.list@...il.com, agraf@...e.de
Subject: Re: [PATCH v17 08/10] ACPI / scan: do not enumerate Indirect IO host children

On Wednesday, March 14, 2018 7:15:57 PM CET John Garry wrote:
> Through the logical PIO framework systems which otherwise have
> no IO space access to legacy ISA/LPC devices may access these
> devices through so-called "indirect IO" method. In this, IO
> space accesses for non-PCI hosts are redirected to a host
> LLDD to manually generate the IO space (bus) accesses. Hosts
> are able to register a region in logical PIO space to map to
> its bus address range.
> 
> Indirect IO child devices have an associated host-specific bus
> address. Special translation is required to map between
> a logical PIO address for a device and it's host bus address.
> 
> Since in the ACPI tables the child device IO resources would
> be the host-specific values, it is required the ACPI scan code
> should not enumerate these devices, and that this should be
> the responsibility of the host driver so that it can "fixup"
> the resources so that they map to the appropriate logical PIO
> addresses.
> 
> To avoid enumerating these child devices, we add a check from
> acpi_device_enumeration_by_parent() as to whether the parent
> for a device is a member of a known list of "indirect IO" hosts.
> For now, the HiSilicon LPC host controller ID is added.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

You have my ACK here already.

Since I've ACKed the [7/10] too, I don't think there's anything more I can do
about this series and I'm assuming that it will be routed through other trees.

Thanks!

> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Tested-by: dann frazier <dann.frazier@...onical.com>
> ---
>  drivers/acpi/scan.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index f9e7904..a4cbf3e 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1524,11 +1524,25 @@ static int acpi_check_serial_bus_slave(struct acpi_resource *ares, void *data)
>  	return -1;
>  }
>  
> +static bool acpi_is_indirect_io_slave(struct acpi_device *device)
> +{
> +	struct acpi_device *parent = device->parent;
> +	const struct acpi_device_id indirect_io_hosts[] = {
> +		{"HISI0191", 0},
> +		{}
> +	};
> +
> +	return parent && !acpi_match_device_ids(parent, indirect_io_hosts);
> +}
> +
>  static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
>  {
>  	struct list_head resource_list;
>  	bool is_serial_bus_slave = false;
>  
> +	if (acpi_is_indirect_io_slave(device))
> +		return true;
> +
>  	/* Macs use device properties in lieu of _CRS resources */
>  	if (x86_apple_machine &&
>  	    (fwnode_property_present(&device->fwnode, "spiSclkPeriod") ||
>