From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH 21/22] drm/tegra: Don't use IOMMU on Tegra20
Date: Thu, 1 Jun 2017 11:36:12 +0300
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To: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Mikko Perttunen <cyndis-/1wQRMveznE@public.gmane.org>, Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, DRI Development <dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>, Erik Faye-Lund <kusmabite-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Nicolas Chauvet <kwizart-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
List-Id: linux-tegra@vger.kernel.org

On 23.05.2017 03:16, Dmitry Osipenko wrote:
> There is no IOMMU on Tegra20, instead a GART would be picked as an IOMMU
> provider.
> 
> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/gpu/drm/tegra/drm.c | 5 ++++-
>  drivers/gpu/host1x/dev.c    | 5 ++++-
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 17416e1c219a..ac8f76d9475f 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -15,6 +15,8 @@
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  
> +#include <soc/tegra/fuse.h>
> +
>  #include "drm.h"
>  #include "gem.h"
>  
> @@ -131,7 +133,8 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
>  	if (!tegra)
>  		return -ENOMEM;
>  
> -	if (iommu_present(&platform_bus_type)) {
> +	if (iommu_present(&platform_bus_type) &&
> +	    tegra_get_chip_id() != TEGRA20) {
>  		u64 carveout_start, carveout_end, gem_start, gem_end;
>  		struct iommu_domain_geometry *geometry;
>  		unsigned long order;
> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
> index 5c1c711a21af..56b7e6d51894 100644
> --- a/drivers/gpu/host1x/dev.c
> +++ b/drivers/gpu/host1x/dev.c
> @@ -25,6 +25,8 @@
>  #include <linux/of.h>
>  #include <linux/slab.h>
>  
> +#include <soc/tegra/fuse.h>
> +
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/host1x.h>
>  #undef CREATE_TRACE_POINTS
> @@ -177,7 +179,8 @@ static int host1x_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> -	if (iommu_present(&platform_bus_type)) {
> +	if (iommu_present(&platform_bus_type) &&
> +	    tegra_get_chip_id() != TEGRA20) {
>  		struct iommu_domain_geometry *geometry;
>  		unsigned long order;
>  
> 

Nicolas noticed that this breaks driver module compilation, as the
`tegra_get_chip_id` is not an exported symbol. I'll consider alternatives to
symbol exporting and will fix it in the new revision of the patch.

-- 
Dmitry