[PATCH v2 4/4] drm/sun4i: Use backend/mixer as dedicated DMA device

[Jernej Škrabec]

Dne sreda, 11. marec 2026 ob 10:49:28 Srednjeevropski standardni čas je Chen-Yu Tsai napisal(a):
> The sun4i DRM driver deals with DMA constraints in a peculiar way.
> Instead of using the actual DMA device in various helpers, it justs
> reconfigures the DMA constraints of the virtual display device using
> the DMA device's device tree node by calling of_dma_configure().
> 
> Turns out of_dma_configure() should only be called from bus code.
> Lately this also triggers a big warning through of_iommu_configure()
> and ultimately __iommu_probe_device():
> 
>     late IOMMU probe at driver bind, something fishy here!
> 
> Now that the GEM DMA helpers have proper support for allocating
> and mapping buffers with a dedicated DMA device, switch over to
> it as the proper solution.
> 
> The mixer change was tested on a Pine H64 model B. The backend change
> was only compile tested. Though I don't expect any issues, help testing
> on an older device would be appreciated.
> 
> Signed-off-by: Chen-Yu Tsai <wenst at chromium.org>

Thanks for fixing this!

Acked-by: Jernej Skrabec <jernej.skrabec at gmail.com>

Best regards,
Jernej