Message-ID: <20251120121416.660781-1-h-shenoy@ti.com>
Date: Thu, 20 Nov 2025 17:44:10 +0530
From: Harikrishna Shenoy <h-shenoy@...com>
To: <Laurent.pinchart@...asonboard.com>, <airlied@...il.com>,
	<andrzej.hajda@...el.com>, <andy.yan@...k-chips.com>,
	<aradhya.bhatia@...ux.dev>, <devarsht@...com>, <dianders@...omium.org>,
	<dri-devel@...ts.freedesktop.org>, <javierm@...hat.com>,
	<jernej.skrabec@...il.com>, <jonas@...boo.se>,
	<linux-kernel@...r.kernel.org>, <linux@...blig.org>,
	<luca.ceresoli@...tlin.com>, <lumag@...nel.org>, <lyude@...hat.com>,
	<maarten.lankhorst@...ux.intel.com>, <mordan@...ras.ru>,
	<mripard@...nel.org>, <neil.armstrong@...aro.org>, <rfoss@...nel.org>,
	<s-jain1@...com>, <simona@...ll.ch>, <tomi.valkeinen@...asonboard.com>,
	<tzimmermann@...e.de>, <u-kumar1@...com>
Subject: [PATCH RESEND v9 0/6]  MHDP8546 fixes related to DRM_BRIDGE_ATTACH_NO_CONNECTOR usecase

With the DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, the connector is 
no longer initialized in  bridge_attach() when the display controller 
sets the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag. 
This causes a null pointer dereference in cdns_mhdp_modeset_retry_fn() 
when trying to access &conn->dev->mode_config.mutex. 
Observed on a board where EDID read failed. 
(log: https://gist.github.com/Jayesh2000/233f87f9becdf1e66f1da6fd53f77429)

Patch 1 adds a connector_ptr which takes care of both 
DRM_BRIDGE_ATTACH_NO_CONNECTOR and !DRM_BRIDGE_ATTACH_NO_CONNECTOR 
case by setting the pointer in appropriate hooks and checking for pointer 
validity before accessing the connector.
Patch 2 adds mode validation hook to bridge fucntions.
Patch 3 fixes HDCP to work with both DRM_BRIDGE_ATTACH_NO_CONNECTOR 
and !DRM_BRIDGE_ATTACH_NO_CONNECTOR case by moving HDCP state handling 
into the bridge atomic check inline with the 
DRM_BRIDGE_ATTACH_NO_CONNECTOR model.
Patches 4,5 do necessary cleanup and alignment for using
connector pointer.

The rationale behind the sequence of commits is we can cleanly 
switch to drm_connector pointer after removal of connector helper 
code blocks, which are anyways not touch after 
DRM_BRIDGE_ATTACH_NO_CONNECTOR has been enabled in driver.

The last patch make smaller adjustment: lowering the log level for
noisy DPCD transfer errors.

v8 patch link:
<https://lore.kernel.org/all/20251014094527.3916421-1-h-shenoy@ti.com/>

Changelog v8-v9:
-Move the patch 6 in v8 related to HDCP to patch 3 and add fixes tag.
-Update to connector_ptr in HDCP code in patch 1.
-Rebased on next-20251114.

v7 patch link:
<https://lore.kernel.org/all/20250929083936.1575685-1-h-shenoy@ti.com/>

Changelog v7-v8:
-Move patches with firxes tag to top of series with appropriate changes
to them.
-Add R/B tag to patch 
https://lore.kernel.org/all/ae3snoap64r252sbqhsshsadxfmlqdfn6b4o5fgfcmxppglkqf@2lsstfsghzwb/

v6 patch link:
<https://lore.kernel.org/all/20250909090824.1655537-1-h-shenoy@ti.com/>

Changelog v6-v7:
-Update cover letter to explain the series.
-Add R/B tag in PATCH 1 and drop fixes tag as suggested.
-Drop fixes tag in PATCH 2.
-Update the commit messages for clear understanding of changes done in patches.

v5 patch link:
<https://lore.kernel.org/all/20250811075904.1613519-1-h-shenoy@ti.com/>

Changelog v5 -> v6:
-Update cover letter to clarify the series in better way.
-Add Reviewed-by tag to relevant patches.
 
v4 patch link: 
<https://lore.kernel.org/all/20250624054448.192801-1-j-choudhary@ti.com>

Changelog v4->v5:
- Handle HDCP state in bridge atomic check instead of connector 
atomic check
 
v3 patch link:
<https://lore.kernel.org/all/20250529142517.188786-1-j-choudhary@ti.com/>

Changelog v3->v4:
- Fix kernel test robot build warning:
  <https://lore.kernel.org/all/202505300201.2s6r12yc-lkp@intel.com/>

v2 patch link:
<https://lore.kernel.org/all/20250521073237.366463-1-j-choudhary@ti.com/>

Changelog v2->v3:
- Add mode_valid in drm_bridge_funcs to a separate patch
- Remove "if (mhdp->connector.dev)" conditions that were missed in v2
- Split out the move of drm_atomic_get_new_connector_for_encoder()
  to a separate patch
- Drop "R-by" considering the changes in v2[1/3]
- Add Fixes tag to first 4 patches:
  commit c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
  This added DBANC flag in tidss while attaching bridge to the encoder
- Drop RFC prefix

v1 patch link:
<https://lore.kernel.org/all/20250116111636.157641-1-j-choudhary@ti.com/>

Changelog v1->v2:
- Remove !DRM_BRIDGE_ATTACH_NO_CONNECTOR entirely
- Add mode_valid in drm_bridge_funcs[0]
- Fix NULL POINTER differently since we cannot access atomic_state
- Reduce log level in cdns_mhdp_transfer call

[0]: https://lore.kernel.org/all/20240530091757.433106-1-j-choudhary@ti.com/

Harikrishna Shenoy (1):
  drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge
    atomic check

Jayesh Choudhary (5):
  drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector
    earlier in atomic_enable()
  drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to
    drm_bridge_funcs
  drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for
    connector initialisation in bridge
  drm/bridge: cadence: cdns-mhdp8546*: Change drm_connector from
    structure to pointer
  drm/bridge: cadence: cdns-mhdp8546-core: Reduce log level for DPCD
    read/write

 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 258 +++++-------------
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |   2 +-
 .../drm/bridge/cadence/cdns-mhdp8546-hdcp.c   |   8 +-
 3 files changed, 72 insertions(+), 196 deletions(-)

-- 
2.34.1

Powered by blists - more mailing lists