From: Nicolin Chen <nicoleotsuka@gmail.com>
To: Dmitry Osipenko <digetx@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 19:54:35 -0700 [thread overview]
Message-ID: <20201002025434.GA9394@Asurada-Nvidia> (raw)
In-Reply-To: <1b621b9d-cdc3-c7aa-2fa2-d728ae2bbc5d@gmail.com>
On Fri, Oct 02, 2020 at 04:55:34AM +0300, Dmitry Osipenko wrote:
> 02.10.2020 04:07, Nicolin Chen пишет:
> > On Thu, Oct 01, 2020 at 11:33:38PM +0300, Dmitry Osipenko wrote:
> >>>>> If we can't come to an agreement on globalizing mc pointer, would
> >>>>> it be possible to pass tegra_mc_driver through tegra_smmu_probe()
> >>>>> so we can continue to use driver_find_device_by_fwnode() as v1?
> >>>>>
> >>>>> v1: https://lkml.org/lkml/2020/9/26/68
> >>>>
> >>>> tegra_smmu_probe() already takes a struct tegra_mc *. Did you mean
> >>>> tegra_smmu_probe_device()? I don't think we can do that because it isn't
> >>>
> >>> I was saying to have a global parent_driver pointer: similar to
> >>> my v1, yet rather than "extern" the tegra_mc_driver, we pass it
> >>> through egra_smmu_probe() and store it in a static global value
> >>> so as to call tegra_smmu_get_by_fwnode() in ->probe_device().
> >>>
> >>> Though I agree that creating a global device pointer (mc) might
> >>> be controversial, yet having a global parent_driver pointer may
> >>> not be against the rule, considering that it is common in iommu
> >>> drivers to call driver_find_device_by_fwnode in probe_device().
> >>
> >> You don't need the global pointer if you have SMMU OF node.
> >>
> >> You could also get driver pointer from mc->dev->driver.
> >>
> >> But I don't think you need to do this at all. The probe_device() could
> >> be invoked only for the tegra_smmu_ops and then seems you could use
> >> dev_iommu_priv_set() in tegra_smmu_of_xlate(), like sun50i-iommu driver
> >> does.
> >
> > Getting iommu device pointer using driver_find_device_by_fwnode()
> > is a common practice in ->probe_device() of other iommu drivers.
>
> Please give me a full list of the IOMMU drivers which use this method.
>
> > But this requires a device_driver pointer that tegra-smmu doesn't
> > have. So passing tegra_mc_driver through tegra_smmu_probe() will
> > address it.
> >
>
> If you're borrowing code and ideas from other drivers, then at least
> please borrow them from a modern good-looking drivers. And I already
> pointed out that following cargo cult is not always a good idea.
>
> ARM-SMMU isn't a modern driver and it has legacy code. You shouldn't
> copy it blindly. The sun50i-iommu driver was added half year ago, you
> may use it as a reference.
I took a closer look at sun50i-iommu driver. It's a good idea.
I think I can come up with a cleaner one. Will send v4.
Thanks for the advice.
next prev parent reply other threads:[~2020-10-02 3:00 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
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 [this message]
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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