Re: [PATCH v1] drm/rockchip: Set VOP for the DRM DMA device

From: Dmitry Osipenko <dmitry.osipenko@collabora.com>
To: Heiko Stuebner <heiko@sntech.de>,
	Sandy Huang <hjc@rock-chips.com>,
	Andy Yan <andy.yan@rock-chips.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Sebastian Reichel <sebastian.reichel@collabora.com>,
	Daniel Stone <daniels@collabora.com>
Cc: kernel@collabora.com, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v1] drm/rockchip: Set VOP for the DRM DMA device
Date: Thu, 23 Oct 2025 10:19:06 +0300	[thread overview]
Message-ID: <40d18130-4aab-47ad-9ed4-00ff6f594cc3@collabora.com> (raw)
In-Reply-To: <3705026.LM0AJKV5NW@phil>

On 10/23/25 09:56, Heiko Stuebner wrote:
> Hi Dmitry,
> 
> Am Mittwoch, 22. Oktober 2025, 18:19:48 Mitteleuropäische Sommerzeit schrieb Dmitry Osipenko:
>> Use VOP for DMA operations performed by DRM core. Rockchip DRM driver
>> is backed by a virtual device that isn't IOMMU-capable, while VOP is the
>> actual display controller device backed by IOMMU. Fixes "swiotlb buffer
>> is full" warning messages originated from GEM prime code paths.
>>
>> Note, that backporting is non-trivial as this depends on 143ec8d3f9396
>> ("drm/prime: Support dedicated DMA device for dma-buf imports"), which
>> landed in v6.16 and 421be3ee36a4 ("drm/rockchip: Refactor IOMMU
>> initialisation"), which landed in v5.19.
>>
>> Reported-by: Daniel Stone <daniels@collabora.com>
>> Fixes: 2048e3286f34 ("drm: rockchip: Add basic drm driver")
>> Cc: stable@vger.kernel.org # v6.16+
>> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
>> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> 
> just a process remark for now. This v1 so it definitly shouldn't come
> with any Reviewed-by-s pre-applied, because this should happen in public.
> 
> It's not a huge issue here, because I do trust the people involved (you,
> Sebastian, Daniel) and the change is small enough, but please for future
> changes, let Review happen on the list, not on private channels.
> 
> 
> Will look at the change itself when back home.

Thanks. I also felt uncomfortable adding r-b to v1. There was no much
discussion on the change that you can find on [1] and the change is
indeed small, so I just added the r-b. Should've linked it the patch.

[1]
https://gitlab.collabora.com/hardware-enablement/rockchip-3588/linux/-/issues/50

-- 
Best regards,
Dmitry

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