linux-kernel - Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe

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Message-ID: <11aae4e2-6173-bf83-5970-a03f09e31c47@gmail.com>
Date:   Fri, 2 Oct 2020 21:20:43 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Nicolin Chen <nicoleotsuka@...il.com>
Cc:     thierry.reding@...il.com, joro@...tes.org, vdumpa@...dia.com,
        jonathanh@...dia.com, linux-tegra@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device()

02.10.2020 21:01, Nicolin Chen пишет:
> On Fri, Oct 02, 2020 at 05:23:14PM +0300, Dmitry Osipenko wrote:
>> 02.10.2020 09:08, Nicolin Chen пишет:
>>>  static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
>>>  {
>>> -	struct device_node *np = dev->of_node;
>>> -	struct tegra_smmu *smmu = NULL;
>>> -	struct of_phandle_args args;
>>> -	unsigned int index = 0;
>>> -	int err;
>>> -
>>> -	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
>>> -					  &args) == 0) {
>>> -		smmu = tegra_smmu_find(args.np);
>>> -		if (smmu) {
>>> -			err = tegra_smmu_configure(smmu, dev, &args);
>>> -			of_node_put(args.np);
>>> -
>>> -			if (err < 0)
>>> -				return ERR_PTR(err);
>>> -
>>> -			/*
>>> -			 * Only a single IOMMU master interface is currently
>>> -			 * supported by the Linux kernel, so abort after the
>>> -			 * first match.
>>> -			 */
>>> -			dev_iommu_priv_set(dev, smmu);
>>> -
>>> -			break;
>>> -		}
>>> -
>>> -		of_node_put(args.np);
>>> -		index++;
>>> -	}
>>> +	struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
>>>  
>>>  	if (!smmu)
>>>  		return ERR_PTR(-ENODEV);
>>
>> The !smmu can't ever be true now, isn't it? Then please remove it.
> 
> How can you be so sure? Have you read my commit message? The whole
> point of removing the hack in tegra_smmu_probe() is to return the
> ERR_PTR(-ENODEV) here. The bus_set_iommu() will call this function
> when mc->smmu is not assigned it, as it's assigned after we return
> tegra_smmu_probe() while bus_set_iommu() is still in the middle of
> the tegra_smmu_probe().
> 

My bad, I probably missed that was looking at the probe_device(), looks
good then.