Re: [PATCH 2/3] iommu/tegra: smmu: Add device tree support for SMMU

From: Stephen Warren
Date: Mon Apr 23 2012 - 14:27:28 EST

On 04/23/2012 05:58 AM, Hiroshi DOYU wrote:
> Add device tree support for Tegra30 IOMMU(SMMU).

> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c

> + err = of_parse_dma_window(dev->of_node, "dma-window", 0, NULL,
> + &base, &size);

This patch also depends on "dt: Add general DMA window parser" that you
sent earlier.

> + asids = be32_to_cpup(of_get_property(dev->of_node, "asids", NULL));
> + if (!asids)
> + return -ENODEV;

What if of_get_property() fails?

BTW, does the # ASIDs vary? I wonder if it's worth representing it in
the device tree or not. If this driver has a chance of working
unmodified on some future chip just by updating this DT property without
any code changes, then it seems reasonable to have it in DT.
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