From: Dmitry Osipenko <digetx@gmail.com>
To: Rob Herring <robh@kernel.org>, Thierry Reding <thierry.reding@gmail.com>
Cc: Joerg Roedel <joro@8bytes.org>,
Robin Murphy <robin.murphy@arm.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
iommu@lists.linux-foundation.org, devicetree@vger.kernel.org,
linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 06/19] dt-bindings: memory: tegra: Squash tegra20-gart into tegra20-mc
Date: Mon, 20 Aug 2018 22:27:49 +0300 [thread overview]
Message-ID: <b46cac22-9b31-9aa7-7eca-4725156346bb@gmail.com> (raw)
In-Reply-To: <20180820191209.GA28618@bogus>
On 20.08.2018 22:12, Rob Herring wrote:
> On Sat, Aug 18, 2018 at 06:54:17PM +0300, Dmitry Osipenko wrote:
>> Splitting GART and Memory Controller wasn't a good decision that was made
>> back in the day. Given that the GART driver hasn't ever been used by
>> anything in the kernel, we decided that it will be better to correct the
>> mistakes of the past and merge two bindings into a single one. In a result
>
> As a result...
>
>> there is a DT ABI change for the Memory Controller that allows not to
>> break newer kernels using older DT by introducing a new required property,
>> the memory clock. Adding the new clock property also puts the tegra20-mc
>> binding in line with the bindings of the later Tegra generations.
>
> I don't understand this part. It looks to me like you are breaking
> compatibility. The driver failing to probe with an old DT is okay?
Yes, DT compatibility is broken. New driver won't probe/load with the old DT,
that's what we want.
> OS's like OpenSUSE use new DTs with older kernel versions, so you should
> consider how to not break them as well. I guess if all this is optional
> or has been unused, then there shouldn't be a problem.
That's interesting.. Memory Controller isn't optional, I guess we could change
compatible to "nvidia,tegra20-mc-gart".
Thierry, do you have any other suggestions?
next prev parent reply other threads:[~2018-08-20 19:27 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-18 15:54 [PATCH v3 00/19] IOMMU: Tegra GART driver clean up and optimization Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 01/19] iommu/tegra: gart: Remove pr_fmt and clean up includes Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 02/19] iommu/tegra: gart: Clean up driver probe errors handling Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 03/19] iommu/tegra: gart: Ignore devices without IOMMU phandle in DT Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 04/19] iommu: Introduce iotlb_sync_map callback Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 05/19] iommu/tegra: gart: Optimize mapping / unmapping performance Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 06/19] dt-bindings: memory: tegra: Squash tegra20-gart into tegra20-mc Dmitry Osipenko
2018-08-20 19:12 ` Rob Herring
2018-08-20 19:27 ` Dmitry Osipenko [this message]
2018-08-20 19:35 ` Dmitry Osipenko
2018-08-28 10:47 ` Thierry Reding
2018-08-28 13:09 ` Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 07/19] ARM: dts: tegra20: Update Memory Controller node to the new binding Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 08/19] memory: tegra: Don't invoke Tegra30+ specific memory timing setup on Tegra20 Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 09/19] memory: tegra: Adapt to Tegra20 device-tree binding changes Dmitry Osipenko
2018-09-03 21:06 ` Marcel Ziswiler
2018-09-04 8:56 ` Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 10/19] memory: tegra: Read client ID on GART page fault Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 11/19] iommu/tegra: gart: Integrate with Memory Controller driver Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 12/19] iommu/tegra: gart: Fix spinlock recursion Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 13/19] iommu/tegra: gart: Fix NULL pointer dereference Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 14/19] iommu/tegra: gart: Allow only one active domain at a time Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 15/19] iommu/tegra: gart: Don't use managed resources Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 16/19] iommu/tegra: gart: Prepend error/debug messages with "GART:" Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 17/19] iommu/tegra: gart: Don't detach devices from inactive domains Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 18/19] iommu/tegra: gart: Simplify clients-tracking code Dmitry Osipenko
2018-08-18 15:54 ` [PATCH v3 19/19] iommu/tegra: gart: Perform code refactoring Dmitry Osipenko
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