[PATCH 0/3] drm: panfrost: Coherency support

[Neil Armstrong]

Hi Robin,

On 16/09/2020 01:51, Robin Murphy wrote:
> Hi all,
> 
> I polished up my original proof-of-concept a little while back, but now
> that I've got my hands on my Juno again I've been able to actually test
> it to my satisfaction, so here are proper patches!

I tested on the Kkadas VIM3, and yes it fixes the random FAULTS I have *without*:
[  152.417127] panfrost ffe40000.gpu: gpu sched timeout, js=0, config=0x7300, status=0x58, head=0x3091400, tail=0x3091400, sched_job=000000004d83c2d7
[  152.530928] panfrost ffe40000.gpu: js fault, js=1, status=INSTR_INVALID_ENC, head=0x30913c0, tail=0x30913c0
[  152.539797] panfrost ffe40000.gpu: gpu sched timeout, js=1, config=0x7300, status=0x51, head=0x30913c0, tail=0x30913c0, sched_job=0000000038cecaf6
[  156.943505] panfrost ffe40000.gpu: js fault, js=0, status=TILE_RANGE_FAULT, head=0x3091400, tail=0x3091400

but, with this patchset, I get the following fps with kmscube:
Rendered 97 frames in 2.016291 sec (48.108145 fps)
Rendered 206 frames in 4.016723 sec (51.285584 fps)
Rendered 316 frames in 6.017208 sec (52.516052 fps)
Rendered 430 frames in 8.017456 sec (53.632975 fps)

but when I resurrect my BROKEN_NS patchset (simply disabling shareability), I get:
Rendered 120 frames in 2.000143 sec (59.995724 fps)
Rendered 241 frames in 4.016760 sec (59.998605 fps)
Rendered 362 frames in 6.033443 sec (59.998911 fps)
Rendered 482 frames in 8.033531 sec (59.998522 fps)

So I get a performance regression with the dma-coherent approach, even if it's
clearly the cleaner.

So:
Tested-by: Neil Armstrong <narmstrong at baylibre.com>

Neil

> 
> It probably makes sense for patches #1 and #2 to stay together and both
> go via drm-misc, provided Will's OK with that.
> 
> Robin.
> 
> 
> Robin Murphy (3):
>   iommu/io-pgtable-arm: Support coherency for Mali LPAE
>   drm/panfrost: Support cache-coherent integrations
>   arm64: dts: meson: Describe G12b GPU as coherent
> 
>  arch/arm64/boot/dts/amlogic/meson-g12b.dtsi | 4 ++++
>  drivers/gpu/drm/panfrost/panfrost_device.h  | 1 +
>  drivers/gpu/drm/panfrost/panfrost_drv.c     | 2 ++
>  drivers/gpu/drm/panfrost/panfrost_gem.c     | 2 ++
>  drivers/gpu/drm/panfrost/panfrost_mmu.c     | 1 +
>  drivers/iommu/io-pgtable-arm.c              | 5 ++++-
>  6 files changed, 14 insertions(+), 1 deletion(-)
>