Re: [PATCH 0/7] drm/msm/dpu: simplify VBIF handling

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 2/27/26 7:36 PM, Dmitry Baryshkov wrote:
> Once Konrad asked, what is the use for VBIF_NRT. Answering to his
> question revealed that it's not actually used by the DPU driver.
> 
> There are two VBIF interfaces two memory, VBIF_RT and VBIF_NRT with
> VBIF_NRT being used only for the offscreen rotator, a separate block
> performing writeback operation with the optional 90 degree rotation.
> This block will require a separate isntance of the DPU driver, and it is
> not supported at this point.

(in case someone interested is reading this - patches welcome!)

> The only exception to that rule is MSM8996, where VBIF_NRT has also been
> used for outputting all writeback data. The DPU driver don't support WB
> on that platform and most likely will not in the close feature.

Unfortunately, it seems that way. Fortunately, it seems like it's indeed
isolated to MSM8996.

This patchset is tearing out a lot of abstraction (which would only be
useful for that SoC though) - if someone decides to work on it, do you
think this should be effectively reverted, or should the NRT VBIF be
instantiated in some other, more locallized way?

Konrad