linux-kernel - Re: How to specify IOMMU'able devices in DT (was: [RFC 0/5] ARM: dma-mapping: New dma_map

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Date:	Mon, 24 Sep 2012 13:28:01 +0400
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Hiroshi Doyu <hdoyu@...dia.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	Joerg Roedel <joerg.roedel@....com>,
	Arnd Bergmann <arnd@...db.de>,
	"m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
	Krishna Reddy <vdumpa@...dia.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"minchan@...nel.org" <minchan@...nel.org>,
	"chunsang.jeong@...aro.org" <chunsang.jeong@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"subashrp@...il.com" <subashrp@...il.com>,
	"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
	"pullip.cho@...sung.com" <pullip.cho@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: How to specify IOMMU'able devices in DT (was: [RFC 0/5] ARM:
 dma-mapping: New dma_map_ops to control IOVA more precisely)

On Mon, 2012-09-24 at 12:04 +0300, Hiroshi Doyu wrote:
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index a1a7225..9eae3be 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -21,6 +21,8 @@
>  #include <linux/slab.h>
>  #include <linux/pm_runtime.h>
> 
> +#include <asm/dma-iommu.h>
> +
>  #include "base.h"
> 
>  #define to_platform_driver(drv)        (container_of((drv), struct
> platform_driver, \
> @@ -305,8 +307,19 @@ int platform_device_add(struct platform_device
> *pdev)
>                  dev_name(&pdev->dev), dev_name(pdev->dev.parent));
> 
>         ret = device_add(&pdev->dev);
> -       if (ret == 0)
> -               return ret;
> +       if (ret)
> +               goto failed;
> +
> +#ifdef CONFIG_PLATFORM_ENABLE_IOMMU
> +       if (platform_bus_type.map && !pdev->dev.archdata.mapping) {
> +               ret = arm_iommu_attach_device(&pdev->dev,
> +                                             platform_bus_type.map);
> +               if (ret)
> +                       goto failed;

This is horrible ... you're adding an architecture specific callback
into our generic code; that's really a no-no.  If the concept of
CONFIG_PLATFORM_ENABE_IOMMU is useful to more than just arm, then this
could become a generic callback.

James


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