Re: [PATCH 3/6] ACPI: add 2 parameters to function acpi dma controller register

[Mika Westerberg <mika.westerberg@linux.intel.com>]

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.