linux-kernel - RE: [PATCH 3/6] ACPI: add 2 parameters to function acpi dma controller register

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Date:	Wed, 6 Jan 2016 06:46:37 +0000
From:	"Wang, Annie" <Annie.Wang@....com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andy.shevchenko@...il.com>
CC:	Vinod Koul <vinod.koul@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	Borislav Petkov <bp@...en8.de>,
	"Huang, Ray" <Ray.Huang@....com>,
	"Wan, Vincent" <Vincent.Wan@....com>, "Xue, Ken" <Ken.Xue@....com>,
	Robin Murphy <robin.murphy@....com>,
	Graeme Gregory <gg@...mlogic.co.uk>,
	"Li, Tony" <Tony.Li@....com>,
	"Yu, Xiangliang" <Xiangliang.Yu@....com>
Subject: RE: [PATCH 3/6] ACPI: add 2 parameters to function acpi dma
 controller register

Hi Mika,

>-----Original Message-----
>From: Mika Westerberg [mailto:mika.westerberg@...ux.intel.com]
>Sent: Monday, January 04, 2016 10:46 PM
>To: Wang, Annie
>Cc: Andy Shevchenko; Vinod Koul; Greg Kroah-Hartman; Rafael J. Wysocki; linux-
>acpi@...r.kernel.org; linux-kernel@...r.kernel.org; linux-serial@...r.kernel.org;
>dmaengine@...r.kernel.org; Borislav Petkov; Huang, Ray; Wan, Vincent; Xue,
>Ken; Robin Murphy; Graeme Gregory; Li, Tony; Yu, Xiangliang
>Subject: Re: [PATCH 3/6] ACPI: add 2 parameters to function acpi dma controller
>register
>
>On Mon, Jan 04, 2016 at 01:31:38PM +0800, Wang Hongcheng wrote:
>> As CSRT table will not always work, 2 arguments, base_request_line and
>> num are added to acpi dma controller register as another way to get
>> device request line.
>>
>> Signed-off-by: Wang Hongcheng <annie.wang@....com>
>> ---
>>  drivers/dma/acpi-dma.c    | 25 ++++++++++++++++++++-----
>>  drivers/dma/dw/platform.c |  2 +-
>>  include/linux/acpi_dma.h  |  6 ++++++
>>  3 files changed, 27 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/dma/acpi-dma.c b/drivers/dma/acpi-dma.c index
>> 16d0daa..e2c27c3 100644
>> --- a/drivers/dma/acpi-dma.c
>> +++ b/drivers/dma/acpi-dma.c
>> @@ -105,7 +105,7 @@ static int acpi_dma_parse_resource_group(const struct
>acpi_csrt_group *grp,
>>   * We are using this table to get the request line range of the specific DMA
>>   * controller to be used later.
>>   */
>> -static void acpi_dma_parse_csrt(struct acpi_device *adev, struct
>> acpi_dma *adma)
>> +static int acpi_dma_parse_csrt(struct acpi_device *adev, struct
>> +acpi_dma *adma)
>>  {
>>  	struct acpi_csrt_group *grp, *end;
>>  	struct acpi_table_csrt *csrt;
>> @@ -117,7 +117,7 @@ static void acpi_dma_parse_csrt(struct acpi_device
>*adev, struct acpi_dma *adma)
>>  	if (ACPI_FAILURE(status)) {
>>  		if (status != AE_NOT_FOUND)
>>  			dev_warn(&adev->dev, "failed to get the CSRT table\n");
>> -		return;
>> +		return -ENOENT;
>>  	}
>>
>>  	grp = (struct acpi_csrt_group *)(csrt + 1); @@ -128,11 +128,12 @@
>> static void acpi_dma_parse_csrt(struct acpi_device *adev, struct acpi_dma
>*adma)
>>  		if (ret < 0) {
>>  			dev_warn(&adev->dev,
>>  				 "error in parsing resource group\n");
>> -			return;
>> +			return -EINVAL;
>>  		}
>>
>>  		grp = (struct acpi_csrt_group *)((void *)grp + grp->length);
>>  	}
>> +	return 0;
>>  }
>>
>>  /**
>> @@ -140,6 +141,8 @@ static void acpi_dma_parse_csrt(struct acpi_device
>*adev, struct acpi_dma *adma)
>>   * @dev:		struct device of DMA controller
>>   * @acpi_dma_xlate:	translation function which converts a dma specifier
>>   *			into a dma_chan structure
>> + * @base_request_line:  device request line base
>> + * @num:                device request line range
>>   * @data		pointer to controller specific data to be used by
>>   *			translation function
>>   *
>> @@ -152,10 +155,13 @@ static void acpi_dma_parse_csrt(struct
>> acpi_device *adev, struct acpi_dma *adma)  int
>acpi_dma_controller_register(struct device *dev,
>>  		struct dma_chan *(*acpi_dma_xlate)
>>  		(struct acpi_dma_spec *, struct acpi_dma *),
>> +		unsigned short base_request_line,
>> +		unsigned short num,
>>  		void *data)
>
>Can you instead provide custom acpi_dma_xlate when you register the DMA
>controller? That function can then use whatever translation scheme is suitable for
>your platform to get the correct channel.

Acpi_dma_xlate  mainly converts an  acpi_dma  structure into a dma_chan structure.
Without proper request line, wrong acpi_dma structure may be get. 

And as Andy says in http://article.gmane.org/gmane.linux.kernel.iommu/11675 
How about add a hook into acpi_dma_controller_register?

Regards,
Hongcheng (Annie)
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