Date: Mon, 21 May 2012 16:11:52 +0200
From: Thierry Reding <thierry.reding@avionic-design.de>
To: Hiroshi DOYU <hdoyu@nvidia.com>
Cc: linux-tegra@vger.kernel.org, Joerg Roedel <joerg.roedel@amd.com>,
        Stephen Warren <swarren@wwwdotorg.org>,
        Bharat Nihalani <bnihalani@nvidia.com>,
        Vandana Salve <vsalve@nvidia.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] iommu/tegra: gart: Reserve iomem resource
Message-ID: <20120521141152.GA21513@avionic-0098.mockup.avionic-design.de>
References: <1337019127-6863-1-git-send-email-hdoyu@nvidia.com>
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* Hiroshi DOYU wrote:
> GART Register/Aperture range should be reserved.
>=20
> Signed-off-by: Hiroshi DOYU <hdoyu@nvidia.com>
> ---
>  drivers/iommu/tegra-gart.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
>=20
> diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
> index 33a23b6..a431006 100644
> --- a/drivers/iommu/tegra-gart.c
> +++ b/drivers/iommu/tegra-gart.c
> @@ -366,12 +366,18 @@ static int tegra_gart_probe(struct platform_device =
*pdev)
>  		return -ENOMEM;
>  	}
> =20
> -	gart_regs =3D devm_ioremap(dev, res->start, resource_size(res));
> +	gart_regs =3D devm_request_and_ioremap(dev, res);
>  	if (!gart_regs) {
>  		dev_err(dev, "failed to remap GART registers\n");
>  		return -ENXIO;
>  	}
> =20
> +	if (!devm_request_mem_region(dev, res_remap->start,
> +				     resource_size(res_remap), dev_name(dev))) {
> +		dev_err(dev, "failed to reserve GART aperture\n");
> +		return -EBUSY;
> +	}
> +

I'm not so sure that this is a good idea. If the GART driver requests the
GART aperture, then users of the GART aperture (e.g. the DRM driver) will no
longer be able to use it.

Thierry

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