linux-kernel - Re: [Patch v5 1/6] ACPI/PCI: Enhance ACPI core to support sparse IO space

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Date:	Wed, 9 Sep 2015 14:38:02 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Yijing Wang <wangyijing@...wei.com>,
	Len Brown <lenb@...nel.org>, Vivek Goyal <vgoyal@...hat.com>,
	Thierry Reding <treding@...dia.com>,
	Jakub Sitnicki <jsitnicki@...il.com>,
	Lv Zheng <lv.zheng@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, "x86 @ kernel . org" <x86@...nel.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [Patch v5 1/6] ACPI/PCI: Enhance ACPI core to support sparse IO
 space

On 2015/7/30 4:37, Bjorn Helgaas wrote:
> On Tue, Jun 09, 2015 at 12:20:43AM +0800, Jiang Liu wrote:
>> Enhance ACPI resource parsing interfaces to support sparse IO space,
>> which will be used to share common code between x86 and IA64 later.
>>
>> Tested-by: Tony Luck <tony.luck@...el.com>
>> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
>> Reviewed-by: Hanjun Guo <hanjun.guo@...aro.org>
>> ---
>>  drivers/acpi/resource.c |    9 ++++++---
>>  include/linux/ioport.h  |    1 +
>>  2 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
>> index 8244f013f210..fdcc73dad2c1 100644
>> --- a/drivers/acpi/resource.c
>> +++ b/drivers/acpi/resource.c
>> @@ -123,7 +123,7 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
>>  EXPORT_SYMBOL_GPL(acpi_dev_resource_memory);
>>  
>>  static void acpi_dev_ioresource_flags(struct resource *res, u64 len,
>> -				      u8 io_decode)
>> +				      u8 io_decode, u8 translation_type)
>>  {
>>  	res->flags = IORESOURCE_IO;
>>  
>> @@ -135,6 +135,8 @@ static void acpi_dev_ioresource_flags(struct resource *res, u64 len,
>>  
>>  	if (io_decode == ACPI_DECODE_16)
>>  		res->flags |= IORESOURCE_IO_16BIT_ADDR;
>> +	if (translation_type == ACPI_SPARSE_TRANSLATION)
>> +		res->flags |= IORESOURCE_IO_SPARSE;
>>  }
>>  
>>  static void acpi_dev_get_ioresource(struct resource *res, u64 start, u64 len,
>> @@ -142,7 +144,7 @@ static void acpi_dev_get_ioresource(struct resource *res, u64 start, u64 len,
>>  {
>>  	res->start = start;
>>  	res->end = start + len - 1;
>> -	acpi_dev_ioresource_flags(res, len, io_decode);
>> +	acpi_dev_ioresource_flags(res, len, io_decode, 0);
>>  }
>>  
>>  /**
>> @@ -227,7 +229,8 @@ static bool acpi_decode_space(struct resource_win *win,
>>  		acpi_dev_memresource_flags(res, len, wp);
>>  		break;
>>  	case ACPI_IO_RANGE:
>> -		acpi_dev_ioresource_flags(res, len, iodec);
>> +		acpi_dev_ioresource_flags(res, len, iodec,
>> +					  addr->info.io.translation_type);
>>  		break;
>>  	case ACPI_BUS_NUMBER_RANGE:
>>  		res->flags = IORESOURCE_BUS;
>> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
>> index 388e3ae94f7a..24bea087e7af 100644
>> --- a/include/linux/ioport.h
>> +++ b/include/linux/ioport.h
>> @@ -94,6 +94,7 @@ struct resource {
>>  /* PnP I/O specific bits (IORESOURCE_BITS) */
>>  #define IORESOURCE_IO_16BIT_ADDR	(1<<0)
>>  #define IORESOURCE_IO_FIXED		(1<<1)
>> +#define IORESOURCE_IO_SPARSE		(1<<2)
> 
> I don't really like this bit.  We adding a new generic IORESOURCE_* bit
> just for a special case, and it's only used in one place, for one arch,
> during enumeration.
Hi Bjorn,
	Instead of defining a formal flag IORESOURCE_IO_SPARSE, we may
reuse other field in struct resource to pass back the SPARSE flag,
but that's a little dirty. For example, we may reuse res->name field
to carry the SPARSE flag for the IA64 special case.
	Is that OK?
Thanks!
Gerry

> 
> Don't we have a similar problem (struct resource can't express all the
> information from an ACPI resource) for the _TRA value for bridge windows?
> If it's a similar issue, we should solve it in a similar way.
Per my understanding, we just ignore ACPI address space information
which can't be expressed by struct resource.
Thanks!
Gerry

> 
>>  /* PCI ROM control bits (IORESOURCE_BITS) */
>>  #define IORESOURCE_ROM_ENABLE		(1<<0)	/* ROM is enabled, same as PCI_ROM_ADDRESS_ENABLE */
>> -- 
>> 1.7.10.4
>>
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