I found that if I ever had a little mistake in my kernel config,
or device tree, or graphics driver that my system would sit in a loop
at bootup trying again and again and again. An example log was:
msm ae00000.mdss: bound ae01000.mdp (ops 0xffffffe596e951f8)
msm_dsi ae94000.dsi: ae94000.dsi supply gdsc not found, using dummy regulator
msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[drm:ti_sn_bridge_probe] *ERROR* could not find any panel node
...
I finally tracked it down where this was happening:
- msm_pdev_probe() is called.
- msm_pdev_probe() registers drivers. Registering drivers kicks
off processing of probe deferrals.
- component_master_add_with_match() could return -EPROBE_DEFER.
making msm_pdev_probe() return -EPROBE_DEFER.
- When msm_pdev_probe() returned the processing of probe deferrals
happens.
- Loop back to the start.
It looks like we can fix this by marking "mdss" as a "simple-bus".
I have no idea if people consider this the right thing to do or a
hack. Hopefully it's the right thing to do. :-)
Once I do this I notice that my boot gets marginally faster (you
don't need to probe the sub devices over and over) and also if I
have a problem it doesn't loop forever (on my system it still
gets upset about some stuck clocks in that case, but at least I
can boot up).
Unless someone hates this, I'd expect:
- Get Rob H to say that the bindings are OK (if they are) and yell
that these really need to be converted to yaml (they do).
- Get Sean or Rob C to land the bindings and driver patch.
- Get Andy or Bjorn to land the dts bits.
NOTES:
- The first patch could land either way. It's just a cleanup.
- I tried to split the dts files into separate patches to ease
backporting if desired. Also because I can't actually test most
of this hardware myself.
Douglas Anderson (9):
drm/msm: Use the devm variant of of_platform_populate()
dt-bindings: msm/dpu: Add simple-bus to dpu bindings
dt-bindings: msm/mdp5: Add simple-bus to dpu bindings
drm/msm: Avoid manually populating our children if "simple-bus" is
there
arm64: dts: qcom: sc7180: Add "simple-bus" to our mdss node
arm64: dts: qcom: sdm845: Add "simple-bus" to our mdss node
arm64: dts: qcom: msm8916: Add "simple-bus" to our mdss node
arm64: dts: qcom: msm8996: Add "simple-bus" to our mdss node
ARM: dts: qcom: msm8974: Add "simple-bus" to our mdss node
.../devicetree/bindings/display/msm/dpu.txt | 4 ++-
.../devicetree/bindings/display/msm/mdp5.txt | 2 +-
arch/arm/boot/dts/qcom-msm8974.dtsi | 2 +-
arch/arm64/boot/dts/qcom/msm8916.dtsi | 2 +-
arch/arm64/boot/dts/qcom/msm8996.dtsi | 2 +-
arch/arm64/boot/dts/qcom/sc7180.dtsi | 2 +-
arch/arm64/boot/dts/qcom/sdm845.dtsi | 2 +-
drivers/gpu/drm/msm/msm_drv.c | 34 ++++++++-----------
8 files changed, 24 insertions(+), 26 deletions(-)
--
2.27.0.383.g050319c2ae-goog
