[PATCH RFC v2 0/5] drm/msm: external HDMI support for Nexus 5 phone

Brian Masney masneyb at onstation.org
Mon Oct 7 01:45:04 UTC 2019

I am using an Analogix SP6001 SlimPort Micro-USB to 4K HDMI Adapter to
connect my Nexus 5 phone to an external display. The external display is
not fully working yet however I think I'm close. When I plug the cable
into the phone, the interrupt for the hot plug detect GPIO for the HDMI
bridge (Analogix ANX7808) fires and anx78xx_handle_common_int_4() shows
that the interrupt status bit is set to SP_HPD_ESYNC_ERR.

The second hot plug detect pin (for qcom,hdmi-tx-8974 for the MSM
KMS/DRM driver) does not fire, and the clocks are not configured via
msm_hdmi_phy_pll_init(). I suspect that this is the issue that I need to
solve next.

I verified in the downstream MSM sources that IRQ 8 on the mdss is the
correct IRQ number for hdmi-tx. Here's the relevant line from
/proc/interrupts showing that no interrupts are triggered:
93: 0 0 0 0 mdss 8 Edge hdmi_isr.

I'm going to continue digging through the code but I'd appreciate any
suggestions for things to check. I assume that the IRQs for both hot
plug detect pins should fire when I plug the cable in. Unfortunately,
the display doesn't work for me with the downstream kernel and I only
have access to a running downstream kernel over the serial console.

High-level changes since v1:
- Hot plug detect interrupt now working properly on HDMI bridge
- Introduce msm8974 PLL support

I've held back some cosmetic changes to the drivers and only included
the necessary changes required to get this functional. This requires
the following patch I sent out on 2019-09-22 to analogix-anx78xx that
corrects an i2c address:

Brian Masney (5):
  drm/bridge: analogix-anx78xx: add support for avdd33 regulator
  drm/msm/hdmi: add msm8974 PLL support
  ARM: dts: qcom: pm8941: add 5vs2 regulator node
  ARM: dts: qcom: msm8974: add HDMI nodes
  ARM: dts: qcom: msm8974-hammerhead: add support for external display

 .../qcom-msm8974-lge-nexus5-hammerhead.dts    | 142 ++++
 arch/arm/boot/dts/qcom-msm8974.dtsi           |  78 ++
 arch/arm/boot/dts/qcom-pm8941.dtsi            |  10 +
 drivers/gpu/drm/bridge/analogix-anx78xx.c     |  33 +
 drivers/gpu/drm/msm/Makefile                  |   1 +
 drivers/gpu/drm/msm/hdmi/hdmi.h               |   6 +
 drivers/gpu/drm/msm/hdmi/hdmi_phy.c           |   4 +-
 drivers/gpu/drm/msm/hdmi/hdmi_pll_8974.c      | 684 ++++++++++++++++++
 8 files changed, 957 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/msm/hdmi/hdmi_pll_8974.c


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