Re: [Bugfix] x86/PCI/ACPI: Fix regression caused by commit 63f1789ec716

[Bjorn Helgaas <bhelgaas@google.com>]

On Mon, Mar 23, 2015 at 03:22:14PM +0800, Jiang Liu wrote:
> Commit 63f1789ec716("Ignore resources consumed by host bridge itself")
> tries to ignore resources consumed by PCI host bridge itself by
> checking IORESOURCE_WINDOW flag, which causes regression on some
> platforms.

"Do.  Or do not.  There is no try."
[http://www.starwars.com/video/do-or-do-not]

That commit doesn't *try* to do something.  It *does* something.  Just
explain what it does and what's wrong with what it does.

> For example, PC Engines APU.1C platform defines PCI MMIO resources with
> ACPI Memory32Fixed operator as below:
> Name (CRES, ResourceTemplate ()
> {
>     ...
>     WordIO (ResourceProducer, MinFixed, MaxFixed, PosDecode,
>         0x0000,             // Granularity
>         0x0D00,             // Range Minimum
>         0xFFFF,             // Range Maximum
>         0x0000,             // Translation Offset
>         0xF300,             // Length
>         ,, , TypeStatic)
>     Memory32Fixed (ReadOnly,
>         0x000A0000,         // Address Base
>         0x00020000,         // Address Length
>         )
>     Memory32Fixed (ReadOnly,
>         0x00000000,         // Address Base
>         0x00000000,         // Address Length
>         _Y00)
> })
> 
> Memory32Fixed operator doesn't support concept of "producer/consumer"
> and it will be treated as "consumer" by the ACPI resource parsing
> interface, thus cause regression. So the fix is only to check
> "producer/consumer" flag for resources having "producer/consumer" flag.

Apparently the problem is with the Memory32Fixed resources above; it sounds
like we ignore them after 63f1789ec716?  I don't quite understand how this
fix works.  acpi_dev_filter_resource_type() has cases for both
ACPI_RESOURCE_TYPE_FIXED_MEMORY32 and ACPI_RESOURCE_TYPE_ADDRESSxx, but 
this patch only touches the latter, not the
ACPI_RESOURCE_TYPE_FIXED_MEMORY32 case.

Is it even legal to use Memory32Fixed for a bridge window?  Is this just a
BIOS bug?  If so, how do we know this workaround won't break something
else for BIOSes that use Memory32Fixed correctly?

Should this be a BIOS-specific quirk?

Incidentally, I also noticed this change:

  --- dmesg_3.18.0-rc5.txt        2015-03-23 10:49:25.064682404 -0500
  +++ dmesg_4.0.0-rc4.txt 2015-03-23 10:49:29.276630002 -0500
  -ACPI: PCI Interrupt Link [INTA] (IRQs 3 4 5 7 10 11 12 15) *0, disabled.
  +ACPI: PCI Interrupt Link [INTA] (IRQs 3 4 5 7 10 11 12 15) *0

Is it intentional that INTA was previously reported as disabled but isn't
any more?

And there's also this:

  acpi PNP0A03:00: [Firmware Bug]: no secondary bus range in _CRS

That isn't a change (it was there in 3.18, too), but that really is a
pretty basic BIOS bug and indicates that we shouldn't be too surprised if
it has other bugs.

> Another possible fix is to only ignore IO resource consumed by host
> bridge and keep IOMEM resource consumed by host bridge, please refer to:
> http://www.spinics.net/lists/linux-pci/msg39706.html

It'd be nice to have Bernhard's logs archived somewhere and referenced
here.  This seems like a dusty corner of the code that might have to be
revisited someday.

> Fixes: 63f1789ec716("Ignore resources consumed by host bridge itself")
> Reported-by: Bernhard Thaler <bernhard.thaler@wvnet.at>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
> Hi Bernhard,
> 	Could you please also help to test whether this patch works for
> you too?
> Thanks!
> Gerry
> ---
>  arch/x86/pci/acpi.c     |    5 ++---
>  drivers/acpi/resource.c |    3 +++
>  2 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index e4695985f9de..8c4b1201f340 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -337,7 +337,7 @@ static void probe_pci_root_info(struct pci_root_info *info,
>  	info->bridge = device;
>  	ret = acpi_dev_get_resources(device, list,
>  				     acpi_dev_filter_resource_type_cb,
> -				     (void *)(IORESOURCE_IO | IORESOURCE_MEM));
> +				     (void *)(IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_WINDOW));

Tangent: I'm disappointed that ia64 didn't get reworked to track the x86
code here.  Is that coming soon?

>  	if (ret < 0)
>  		dev_warn(&device->dev,
>  			 "failed to parse _CRS method, error code %d\n", ret);
> @@ -346,8 +346,7 @@ static void probe_pci_root_info(struct pci_root_info *info,
>  			"no IO and memory resources present in _CRS\n");
>  	else
>  		resource_list_for_each_entry_safe(entry, tmp, list) {
> -			if ((entry->res->flags & IORESOURCE_WINDOW) == 0 ||
> -			    (entry->res->flags & IORESOURCE_DISABLED))
> +			if (entry->res->flags & IORESOURCE_DISABLED)
>  				resource_list_destroy_entry(entry);
>  			else
>  				entry->res->name = info->name;
> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> index 5589a6e2a023..b0d3f2ceef06 100644
> --- a/drivers/acpi/resource.c
> +++ b/drivers/acpi/resource.c
> @@ -606,6 +606,9 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares,
>  	case ACPI_RESOURCE_TYPE_ADDRESS32:
>  	case ACPI_RESOURCE_TYPE_ADDRESS64:
>  	case ACPI_RESOURCE_TYPE_EXTENDED_ADDRESS64:
> +		if (((types & IORESOURCE_WINDOW) == 0) ^
> +		    (ares->data.address.producer_consumer == ACPI_CONSUMER))
> +			break;
>  		if (ares->data.address.resource_type == ACPI_MEMORY_RANGE)
>  			type = IORESOURCE_MEM;
>  		else if (ares->data.address.resource_type == ACPI_IO_RANGE)
> -- 
> 1.7.10.4
>