Re: [PATCH 1/6] iommu/tegra124: smmu: optionaly AHB enables SMMU

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 12/05/2013 05:25 AM, Hiroshi Doyu wrote:
> SMMU used to depend on AHB bus. AHB driver needs to be populated and
> AHB_XBAR_CTRL_SMMU_INIT_DONE bit needs to be set earliear than SMMU
> being populated. Later Tegra SoC (>= T124) doesn't need AHB to enable
> SMMU on AHB_XBAR_CTRL for AHB_XBAR_CTRL_SMMU_INIT_DONE any more. This
> setting bit is now optional, depending on DT passing ahb phandle or
> not.

This patch should happen after 1/3, and the "platform data" should
indicate whether tegra_ahb_enable_smmu() needs to be called, so that on
Tegra30...

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

> @@ -1284,9 +1287,6 @@ static int tegra_smmu_probe(struct platform_device *pdev)

>  	smmu->ahb = of_parse_phandle(dev->of_node, "nvidia,ahb", 0);
> -	if (!smmu->ahb)
> -		return -ENODEV;

... that error-checking is still in place, yet on Tegra124,
of_parse_phandle() isn't even called.