linux-kernel - Re: [V4 PATCH 4/6] device property: Introduces device_dma_is

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Message-ID: <555CFD7D.5090208@amd.com>
Date:	Wed, 20 May 2015 16:32:45 -0500
From:	Suravee Suthikulanit <suravee.suthikulpanit@....com>
To:	Will Deacon <will.deacon@....com>
CC:	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"lenb@...nel.org" <lenb@...nel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"thomas.lendacky@....com" <thomas.lendacky@....com>,
	"herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"arnd@...db.de" <arnd@...db.de>,
	"msalter@...hat.com" <msalter@...hat.com>,
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	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
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Subject: Re: [V4 PATCH 4/6] device property: Introduces device_dma_is_coherent()

On 5/20/2015 5:28 AM, Will Deacon wrote:
> On Fri, May 15, 2015 at 10:23:12PM +0100, Suravee Suthikulpanit wrote:
>> Currently, device drivers, which support both OF and ACPI,
>> need to call two separate APIs, of_dma_is_coherent() and
>> acpi_dma_is_coherent()) to determine device coherency attribute.
>>
>> This patch simplifies this process by introducing a new device
>> property API, device_dma_is_coherent(), which calls the appropriate
>> interface based on the booting architecture.
>>
>> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
>> CC: Rafael J. Wysocki <rjw@...ysocki.net>
>> ---
>>   drivers/base/property.c  | 12 ++++++++++++
>>   include/linux/property.h |  2 ++
>>   2 files changed, 14 insertions(+)
>>
>> diff --git a/drivers/base/property.c b/drivers/base/property.c
>> index 1d0b116..8123c6e 100644
>> --- a/drivers/base/property.c
>> +++ b/drivers/base/property.c
>> @@ -14,6 +14,7 @@
>>   #include <linux/export.h>
>>   #include <linux/kernel.h>
>>   #include <linux/of.h>
>> +#include <linux/of_address.h>
>>   #include <linux/property.h>
>>
>>   /**
>> @@ -519,3 +520,14 @@ unsigned int device_get_child_node_count(struct device *dev)
>>   	return count;
>>   }
>>   EXPORT_SYMBOL_GPL(device_get_child_node_count);
>> +
>> +bool device_dma_is_coherent(struct device *dev)
>> +{
>> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
>> +		return of_dma_is_coherent(dev->of_node);
>> +	else if (has_acpi_companion(dev))
>> +		return acpi_dma_is_coherent(acpi_node(dev->fwnode));
>
> I don't think you need the has_acpi_companion check, as acpi_node handles
> this and acpi_dma_is_coherent(NULL) returns false.
>
> Will
>
You are right.

Thanks,

Suravee

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