[regression, bisected] rockchip rk3399 video output breakage

From: Jakob Unterwurzacher
Date: Tue Apr 24 2018 - 08:20:14 EST

I am working on getting HDMI output enabled in mainline Linux for our RK3399-Q7 module. It works fine on v4.16, but testing with v4.17-rc2 I get this, and the screen stays black:

[ 7.142712] alloc_contig_range: [7f061, 7f062) PFNs busy
[ 7.148862] alloc_contig_range: [7f066, 7f067) PFNs busy
[ 7.155041] alloc_contig_range: [7f067, 7f068) PFNs busy
[ 7.161139] alloc_contig_range: [7f070, 7f071) PFNs busy
[ 7.167295] alloc_contig_range: [7f071, 7f072) PFNs busy
[ 7.173413] alloc_contig_range: [7f072, 7f073) PFNs busy
[ 7.181387] alloc_contig_range: [7f073, 7f074) PFNs busy
[ 7.190623] alloc_contig_range: [7f074, 7f075) PFNs busy
[ 7.196668] alloc_contig_range: [7f075, 7f076) PFNs busy
[ 7.202793] alloc_contig_range: [7f076, 7f077) PFNs busy
[ 7.254911] hub 7-1:1.0: USB hub found
[ 7.259878] hub 7-1:1.0: 4 ports detected
[ 7.322543] rockchip-drm display-subsystem: master bind failed: -12
[ 7.329619] rockchip-vop: probe of ff900000.vop failed with error -12

Full dmesg: https://gist.github.com/jakob-tsd/33cf395e355bf9bb6956c36438d999e7

I have bisected the "master bind failed" down to:

commit 9176a303d971dc0fb35469c531c0d263667d2277
Author: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
Date: Fri Mar 23 15:38:10 2018 +0800

iommu/rockchip: Use IOMMU device for dma mapping operations

Use the first registered IOMMU device for dma mapping operations, and
drop the domain platform device.

This is similar to exynos iommu driver.

Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>

Moving to one commit earlier brings the screen to life. Just with colorful garbage, but I guess that's a different problem.

Is this a known issue with the IOMMU change?