From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Subject: Re: [PATCHv3 10/19] iommu/tegra: smmu: Get "nvidia,swgroups" from
 DT
Date: Wed, 30 Oct 2013 16:22:38 -0600
Message-ID: <527186AE.7080104@wwwdotorg.org>
References: <1382092020-13170-1-git-send-email-hdoyu@nvidia.com> <1382092020-13170-11-git-send-email-hdoyu@nvidia.com> <20131024085811.A3F2CC4039D@trevor.secretlab.ca>
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To: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>, Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: devicetree@vger.kernel.org

On 10/24/2013 02:58 AM, Grant Likely wrote:
> On Fri, 18 Oct 2013 13:26:51 +0300, Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> wrote:
>> This provides the info about which H/W Accelerators are supported on
>> Tegra SoC. This info is passed from DT. This is necessary to have the
>> unified SMMU driver among Tegra SoCs. Instead of using platform data,
>> DT passes "nvidia,swgroups" now. DT is mandatory in Tegra.
>>
>> Signed-off-by: Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>> @@ -1200,6 +1193,9 @@ static int tegra_smmu_probe(struct platform_device *pdev)
>>  	if (of_property_read_u32(dev->of_node, "nvidia,#asids", &asids))
>>  		return -ENODEV;
>>  
>> +	if (of_property_read_u64(dev->of_node, "nvidia,swgroups", &swgroups))
>> +		return -ENODEV;
>> +
> 
> Best practice: A new property has been created here. If the property
> isn't present, then it should default to the previous meaning instead of
> outright failing. (or make a strong argument that no one is using this
> yet and therefore is not breakage).

We definitely don't have anyone using this binding yet upstream, and
even the reg properties in the DT were wrong for the device, so it
couldn't possibly have worked:-(