[PATCH 2/2] drm/etnaviv: use CMA area to compute linear window offset if possible

[Primoz Fiser]

Hi,

what happened to these patches? In thread "[REGRESSION] drm/etnaviv: command
buffer outside valid memory window" [1] it was mentioned these got "shot
down" due to layering violations, but no official correspondence has been
found? Is is due to exporting symbols from mm/cma.c in [1/2] and why is this
an issue?

We are still affected by issue these patches tried to address and we are
interested in getting the solution into mainline.

Patches were integrated (small fix required due to renamed include file header)
and tested on latest master with PHYTEC's 2GiB phyCORE SoM and cma=256M kernel
cmdline parameter.

Without patches:

[    7.892954] etnaviv etnaviv: bound 130000.gpu (ops gpu_ops)
[    7.901286] etnaviv etnaviv: bound 134000.gpu (ops gpu_ops)
[    7.909809] etnaviv etnaviv: bound 2204000.gpu (ops gpu_ops)
[    7.915775] etnaviv-gpu 130000.gpu: model: GC2000, revision: 5108
[    7.924000] etnaviv-gpu 134000.gpu: model: GC320, revision: 5007
[    7.930615] etnaviv-gpu 2204000.gpu: model: GC355, revision: 1215
[    7.936934] etnaviv-gpu 2204000.gpu: Ignoring GPU with VG and FE2.0
[    7.948600] [drm] Initialized etnaviv 1.3.0 20151214 for etnaviv on minor 1
[   16.656092] etnaviv etnaviv: command buffer outside valid memory window
[   16.695777] etnaviv etnaviv: command buffer outside valid memory window
[   16.765654] etnaviv etnaviv: command buffer outside valid memory window
[   16.800111] etnaviv etnaviv: command buffer outside valid memory window

NOTE: See "command buffer outside valid memory window" errors when trying to
use GPU.

With patches:

[    7.708159] etnaviv etnaviv: bound 130000.gpu (ops gpu_ops)
[    7.716095] etnaviv etnaviv: bound 134000.gpu (ops gpu_ops)
[    7.724257] etnaviv etnaviv: bound 2204000.gpu (ops gpu_ops)
[    7.730205] etnaviv-gpu 130000.gpu: model: GC2000, revision: 5108
[    7.738407] etnaviv-gpu 134000.gpu: model: GC320, revision: 5007
[    7.745039] etnaviv-gpu 2204000.gpu: model: GC355, revision: 1215
[    7.751365] etnaviv-gpu 2204000.gpu: Ignoring GPU with VG and FE2.0
[    7.762876] [drm] Initialized etnaviv 1.3.0 20151214 for etnaviv on minor 1

NOTE: No errors, GPU fully functional!

In the end, it looks like we are not the only ones with the same issues as
patch "drm/etnaviv: optionally set gpu linear window to cma area"  that
addresses the same issue was submitted by Sven Van Asbroeck (see [2]). 
Unfortunately, his solution was also not accepted.

Please advise what would be the best solution implementation and how to
proceed in this case?

BR,
Primoz

[1] https://lists.freedesktop.org/archives/dri-devel/2019-June/223516.html

[2] https://lore.kernel.org/dri-devel/20190619183856.467-1-TheSven73@gmail.com/