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SubjectRE: [PATCH 3/6] ACPI: add 2 parameters to function acpi dma controller register
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Hi Mika,

>-----Original Message-----
>From: Mika Westerberg [mailto:mika.westerberg@linux.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@vger.kernel.org; linux-kernel@vger.kernel.org; linux-serial@vger.kernel.org;
>dmaengine@vger.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@amd.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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