[RFC PATCH] drm/msm: lookup the ICC paths in both mdp5/dpu and mdss devices

[Marijn Suijten]

On 2022-08-26 12:16:40, Dmitry Baryshkov wrote:
> On 05/08/2022 15:24, Marijn Suijten wrote:
> > On 2022-08-05 14:56:30, Dmitry Baryshkov wrote:
> >> The commit 6874f48bb8b0 ("drm/msm: make mdp5/dpu devices master
> >> components") changed the MDP5 driver to look for the interconnect paths
> >> in the MDSS device rather than in the MDP5 device itself. This was left
> >> unnoticed since on my testing devices the interconnects probably didn't
> >> reach the sync state.
> >>
> >> Rather than just using the MDP5 device for ICC path lookups for the MDP5
> >> devices, introduce an additional helper to check both MDP5/DPU and MDSS
> >> nodes. This will be helpful for the MDP5->DPU conversion, since the
> >> driver will have to check both nodes.
> >>
> >> Fixes: 6874f48bb8b0 ("drm/msm: make mdp5/dpu devices master components")
> >> Reported-by: Marijn Suijten <marijn.suijten at somainline.org>
> >> Reported-by: Yassine Oudjana <y.oudjana at protonmail.com>
> >> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > 
> > Tested-by: Marijn Suijten <marijn.suijten at somainline.org> # On sdm630
> > 
> > But I'm not sure about giving my Reviewed-by to this, as I'd rather
> > *correct* the DT bindings for sdm630 and msm8996 to provide
> > interconnects in the MDSS node unless there are strong reasons not to
> > (and I don't consider "backwards compatibility" to be one, this binding
> > "never even existed" if mdp5.txt is to be believed).
> 
> As a kind of a joke, I'd prefer to have interconnects in the mdp/dpu 
> device node. In the end, the interconnects describe the path between the 
> display controller and the DDR, not the path between the whole MDSS and DDR.
> 
> So, for next chipsets I'd vote to move icc to dpu/mdp node (and maybe 
> even move existing inerconnects to the dpu node).

Sure.  In that case, do you want to rework this patch / code again to
only look in the DPU/MDP, and not at MDSS at all?  (Or is that another
DT API break we'd rather not make?)

- Marijn