Re: [V4 PATCH 4/6] device property: Introduces device_dma_is_coherent()

[Will Deacon <will.deacon@arm.com>]

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@amd.com>
> CC: Rafael J. Wysocki <rjw@rjwysocki.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