From: Dmitry Osipenko <digetx@gmail.com>
To: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
joro@8bytes.org, krzk@kernel.org, vdumpa@nvidia.com,
jonathanh@nvidia.com, linux-tegra@vger.kernel.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev
Date: Thu, 1 Oct 2020 05:06:19 +0300 [thread overview]
Message-ID: <72b11925-5857-8ce5-d084-cab01ca1b396@gmail.com> (raw)
In-Reply-To: <20201001012630.GA28240@Asurada-Nvidia>
01.10.2020 04:26, Nicolin Chen пишет:
> On Thu, Oct 01, 2020 at 12:56:46AM +0300, Dmitry Osipenko wrote:
>> 01.10.2020 00:32, Nicolin Chen пишет:
>>> On Thu, Oct 01, 2020 at 12:24:25AM +0300, Dmitry Osipenko wrote:
>>>> ...
>>>>>> It looks to me like the only reason why you need this new global API is
>>>>>> because PCI devices may not have a device tree node with a phandle to
>>>>>> the IOMMU. However, SMMU support for PCI will only be enabled if the
>>>>>> root complex has an iommus property, right? In that case, can't we
>>>>>> simply do something like this:
>>>>>>
>>>>>> if (dev_is_pci(dev))
>>>>>> np = find_host_bridge(dev)->of_node;
>>>>>> else
>>>>>> np = dev->of_node;
>>>>>>
>>>>>> ? I'm not sure exactly what find_host_bridge() is called, but I'm pretty
>>>>>> sure that exists.
>>>>>>
>>>>>> Once we have that we can still iterate over the iommus property and do
>>>>>> not need to rely on this global variable.
>>>>>
>>>>> I agree that it'd work. But I was hoping to simplify the code
>>>>> here if it's possible. Looks like we have an argument on this
>>>>> so I will choose to go with your suggestion above for now.
>>>>
>>>> This patch removed more lines than were added. If this will be opposite
>>>> for the Thierry's suggestion, then it's probably not a great suggestion.
>>>
>>> Sorry, I don't quite understand this comments. Would you please
>>> elaborate what's this "it" being "not a great suggestion"?
>>>
>>
>> I meant that you should try to implement Thierry's solution, but if the
>> end result will be worse than the current patch, then you shouldn't make
>> a v4, but get back to this discussion in order to choose the best option
>> and make everyone agree on it.
>
> I see. Thanks for the reply. And here is a sample implementation:
That's what I supposed to happen :) The new variant adds code and
complexity, while old did the opposite. Hence the old variant is clearly
more attractive, IMO.
next prev parent reply other threads:[~2020-10-01 2:06 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 8:42 [PATCH v3 0/3] iommu/tegra-smmu: Add PCI support Nicolin Chen
2020-09-30 8:42 ` [PATCH v3 1/3] memory: tegra: Add devm_tegra_get_memory_controller() Nicolin Chen
2020-09-30 9:07 ` Krzysztof Kozlowski
2020-09-30 9:41 ` Nicolin Chen
2020-09-30 10:27 ` Krzysztof Kozlowski
2020-09-30 14:41 ` Dmitry Osipenko
2020-09-30 14:45 ` Krzysztof Kozlowski
2020-09-30 15:22 ` Dmitry Osipenko
2020-09-30 15:23 ` Thierry Reding
2020-09-30 15:27 ` Dmitry Osipenko
2020-09-30 15:53 ` Dmitry Osipenko
2020-09-30 16:03 ` Thierry Reding
2020-09-30 16:06 ` Dmitry Osipenko
2020-09-30 16:15 ` Thierry Reding
2020-09-30 16:26 ` Dmitry Osipenko
2020-09-30 16:38 ` Thierry Reding
2020-09-30 17:32 ` Dmitry Osipenko
2020-09-30 8:42 ` [PATCH v3 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev Nicolin Chen
2020-09-30 9:21 ` Krzysztof Kozlowski
2020-09-30 9:40 ` Nicolin Chen
2020-09-30 10:19 ` Krzysztof Kozlowski
2020-09-30 14:41 ` Dmitry Osipenko
2020-09-30 15:09 ` Dmitry Osipenko
2020-09-30 20:51 ` Nicolin Chen
2020-09-30 15:31 ` Thierry Reding
2020-09-30 15:36 ` Dmitry Osipenko
2020-09-30 16:06 ` Thierry Reding
2020-09-30 16:25 ` Dmitry Osipenko
2020-09-30 16:47 ` Thierry Reding
2020-10-01 2:11 ` Dmitry Osipenko
2020-10-01 7:58 ` Thierry Reding
2020-10-01 19:04 ` Dmitry Osipenko
2020-10-05 9:16 ` Thierry Reding
2020-10-05 9:38 ` Dmitry Osipenko
2020-10-05 10:27 ` Thierry Reding
2020-09-30 16:10 ` Thierry Reding
2020-09-30 16:29 ` Dmitry Osipenko
2020-10-01 7:59 ` Thierry Reding
2020-09-30 20:36 ` Nicolin Chen
2020-09-30 21:24 ` Dmitry Osipenko
2020-09-30 21:32 ` Nicolin Chen
2020-09-30 21:56 ` Dmitry Osipenko
2020-10-01 1:26 ` Nicolin Chen
2020-10-01 2:06 ` Dmitry Osipenko [this message]
2020-10-01 2:48 ` Nicolin Chen
2020-10-01 4:04 ` Dmitry Osipenko
2020-10-01 10:23 ` Thierry Reding
2020-10-01 11:04 ` Nicolin Chen
2020-10-01 20:33 ` Dmitry Osipenko
2020-10-02 1:07 ` Nicolin Chen
2020-10-02 1:55 ` Dmitry Osipenko
2020-10-02 2:54 ` Nicolin Chen
2020-10-05 7:24 ` Thierry Reding
2020-10-05 7:13 ` Thierry Reding
2020-10-05 8:14 ` Dmitry Osipenko
2020-10-05 9:31 ` Thierry Reding
2020-10-01 9:54 ` Thierry Reding
2020-10-01 9:51 ` Thierry Reding
2020-10-01 10:33 ` Nicolin Chen
2020-10-01 10:42 ` Thierry Reding
2020-10-01 9:47 ` Thierry Reding
2020-10-01 10:46 ` Thierry Reding
2020-10-02 1:29 ` Nicolin Chen
2020-09-30 8:42 ` [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support Nicolin Chen
2020-09-30 14:53 ` Dmitry Osipenko
2020-09-30 20:03 ` Nicolin Chen
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