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[v2,0/2] "no-hpd" support in CDNS DP bridge driver

Message ID 20230405142440.191939-1-j-choudhary@ti.com (mailing list archive)
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Series "no-hpd" support in CDNS DP bridge driver | expand

Message

Jayesh Choudhary April 5, 2023, 2:24 p.m. UTC 
In J721s2 EVM, DP0 HPD is not connected to correct HPD pin on SOC
which results in HPD detect as always connnected, so when display
is not connected driver continuously retries to read EDID and DPCD
registers.

To handle such cases add support for no hpd configuration in
cdns-mhdp driver.

DT changes for display in j721s2 will be posted once we have no-hpd
support and multilink DP support[1] merged.

[1]:
<https://lore.kernel.org/all/20230227133104.29788-1-sjakhade@cadence.com/>

Changelog v1->v2:
- edit the commit message for the bindings to clarify why we exactly need
  no-hpd indication for mhdp.

v1 patch-link:
<https://lore.kernel.org/all/20230316140823.234263-1-j-choudhary@ti.com/>

Rahul T R (2):
  dt-bindings: drm/bridge: Add no-hpd property
  drm: bridge: cdns-mhdp8546: Add support for no-hpd

 .../display/bridge/cdns,mhdp8546.yaml         |  6 +++
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 37 ++++++++++++++++---
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  1 +
 3 files changed, 39 insertions(+), 5 deletions(-)

Comments

Tomi Valkeinen April 17, 2023, 8:47 a.m. UTC | #1 
On 05/04/2023 17:24, Jayesh Choudhary wrote:
> In J721s2 EVM, DP0 HPD is not connected to correct HPD pin on SOC
> which results in HPD detect as always connnected, so when display
> is not connected driver continuously retries to read EDID and DPCD
> registers.

Where is the DP0 HPD connected to? Nowhere? If it's connected to a pin, 
can that pin be used as a GPIO? In other words, do we have a HPD, just 
not with mhdp, or is there just no HPD at all?

  Tomi