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From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: geert+renesas@glider.be, dri-devel@lists.freedesktop.org,
	linux-tegra@vger.kernel.org, laurent.pinchart@ideasonboard.com,
	will@kernel.org, hch@lst.de, linux-samsung-soc@vger.kernel.org,
	magnus.damm@gmail.com, linux@armlinux.org.uk,
	jonathanh@nvidia.com, agross@kernel.org,
	kyungmin.park@samsung.com, linux-media@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, inki.dae@samsung.com,
	linux-mediatek@lists.infradead.org, matthias.bgg@gmail.com,
	linux-arm-kernel@lists.infradead.org, sw0312.kim@samsung.com,
	linux-kernel@vger.kernel.org, t-kristo@ti.com,
	iommu@lists.linux-foundation.org,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 16/18] staging/media/tegra-vde: Clean up IOMMU workaround
Date: Sun, 30 Aug 2020 22:44:38 +0300	[thread overview]
Message-ID: <f6240633-feed-70b7-2fe8-49fcee687676@gmail.com> (raw)
In-Reply-To: <20200827155446.GB1660457@ulmo>

27.08.2020 18:54, Thierry Reding пишет:
...
>> The Tegra DRM has a very special quirk for ARM32 that was added in this
>> commit [2] and driver relies on checking of whether explicit or implicit
>> IOMMU is used in order to activate the quirk.
>>
>> [2]
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=273da5a046965ccf0ec79eb63f2d5173467e20fa
>>
>> Once the implicit IOMMU is used for the DRM driver, the quirk no longer
>> works (if I'm not missing something). This problem needs to be resolved
>> before implicit IOMMU could be used by the Tegra DRM on ARM32.
...
> I do have a patch lying around somewhere that implements the mapping
> cache that was referenced in the above commit. Let me know if I should
> dig that up and send it out.

Hello, Thierry! It certainly will be interesting to take a look at yours
patch!

I think that the caching shouldn't be strictly necessary for keeping the
current workaround working and it should be possible to keep the code
as-is by replacing the domain-type checking with the SoC-generation
check in the Tegra DRM driver.

In general, IMO it should be better to stash the complex changes until
we'll get closer to adopting the new UAPI as it will certainly touch the
aspect of the per-device mappings. But if yours patch is less than 100
LOC, then maybe we could consider applying it right now!
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  reply	other threads:[~2020-08-30 19:44 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200820150857eucas1p18f5f2ad87703a68b6ed20a090f7c1c57@eucas1p1.samsung.com>
2020-08-20 15:08 ` [PATCH 00/18] Convert arch/arm to use iommu-dma Robin Murphy
2020-08-20 15:08   ` [PATCH 01/18] ARM/dma-mapping: Drop .dma_supported for IOMMU ops Robin Murphy
2020-08-20 15:08   ` [PATCH 02/18] ARM/dma-mapping: Consolidate IOMMU ops callbacks Robin Murphy
2020-08-20 15:08   ` [PATCH 03/18] ARM/dma-mapping: Merge IOMMU ops Robin Murphy
2020-08-20 15:08   ` [PATCH 04/18] iommu/dma: Add temporary hacks for arch/arm Robin Murphy
2020-08-20 15:08   ` [PATCH 05/18] ARM/dma-mapping: Switch to iommu_dma_ops Robin Murphy
2020-09-28 11:32     ` Marek Szyprowski
2020-08-20 15:08   ` [PATCH 06/18] ARM/dma-mapping: Support IOMMU default domains Robin Murphy
2020-08-20 15:08   ` [PATCH 07/18] iommu/arm-smmu: Remove arch/arm workaround Robin Murphy
2020-08-21  8:07     ` Will Deacon
2020-08-20 15:08   ` [PATCH 08/18] iommu/renesas: " Robin Murphy
2020-08-20 15:08   ` [PATCH 09/18] iommu/mediatek-v1: Add IOMMU_DOMAIN_DMA support Robin Murphy
2020-08-29  9:54     ` Yong Wu
2020-08-20 15:08   ` [PATCH 10/18] iommu/msm: " Robin Murphy
2020-08-20 15:55     ` Rob Clark
2020-08-20 16:58       ` Robin Murphy
2020-08-20 17:05         ` Rob Clark
2020-08-20 15:08   ` [PATCH 11/18] iommu/omap: " Robin Murphy
2020-08-24 21:39     ` Suman Anna via iommu
2020-08-20 15:08   ` [PATCH 12/18] iommu/tegra-gart: " Robin Murphy
2020-08-20 20:16     ` Dmitry Osipenko
2020-08-21  0:28       ` Robin Murphy
2020-08-23 21:42         ` Dmitry Osipenko
2020-08-20 15:08   ` [PATCH 13/18] iommu/tegra: " Robin Murphy
2020-08-27 15:45     ` Thierry Reding
2020-08-27 18:18       ` Robin Murphy
2020-08-20 15:08   ` [PATCH 14/18] drm/exynos: Consolidate IOMMU mapping code Robin Murphy
2020-09-18 14:30     ` Marek Szyprowski
2020-09-21  2:09     ` Inki Dae
2020-08-20 15:08   ` [PATCH 15/18] drm/nouveau/tegra: Clean up IOMMU workaround Robin Murphy
2020-08-20 15:08   ` [PATCH 16/18] staging/media/tegra-vde: " Robin Murphy
2020-08-20 19:51     ` Dmitry Osipenko
2020-08-20 20:10       ` Dmitry Osipenko
2020-08-21  0:11       ` Robin Murphy
2020-08-23 21:34         ` Dmitry Osipenko
2020-08-24 14:01           ` Robin Murphy
2020-08-27  7:05             ` Dmitry Osipenko
2020-08-27 15:54               ` Thierry Reding
2020-08-30 19:44                 ` Dmitry Osipenko [this message]
2020-08-20 15:08   ` [PATCH 17/18] media/omap3isp: " Robin Murphy
2020-08-20 16:53     ` Sakari Ailus
2020-08-20 17:25       ` Robin Murphy
2020-08-20 19:55         ` Sakari Ailus
2020-08-20 23:01           ` Robin Murphy
2020-08-24 21:55             ` Suman Anna via iommu
2020-08-20 15:08   ` [PATCH 18/18] ARM/dma-mapping: Remove legacy dma-iommu API Robin Murphy
2020-08-24 11:40   ` [PATCH 00/18] Convert arch/arm to use iommu-dma Marek Szyprowski
2020-09-18 15:13     ` Marek Szyprowski
2020-08-27 12:31   ` Aw: " Frank Wunderlich
2020-08-27 12:54     ` Matthias Brugger

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