linux-kernel - [PATCH v6 0/2] Add support for DSC and FEC for cadence MHDP8546 bridge

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Message-ID: <20251224065949.2268373-1-h-shenoy@ti.com>
Date: Wed, 24 Dec 2025 12:29:47 +0530
From: Harikrishna Shenoy <h-shenoy@...com>
To: <andrzej.hajda@...el.com>, <neil.armstrong@...aro.org>,
	<rfoss@...nel.org>, <Laurent.pinchart@...asonboard.com>, <jonas@...boo.se>,
	<jernej.skrabec@...il.com>, <maarten.lankhorst@...ux.intel.com>,
	<mripard@...nel.org>, <tzimmermann@...e.de>, <airlied@...il.com>,
	<simona@...ll.ch>, <dmitry.baryshkov@....qualcomm.com>,
	<sjakhade@...ence.com>, <nathan@...nel.org>, <dianders@...omium.org>,
	<luca.ceresoli@...tlin.com>, <andy.yan@...k-chips.com>, <xiqi2@...wei.com>,
	<mordan@...ras.ru>, <linux-kernel@...r.kernel.org>,
	<dri-devel@...ts.freedesktop.org>, <aradhya.bhatia@...ux.dev>,
	<devarsht@...com>, <s-jain1@...com>, <tomi.valkeinen@...asonboard.com>,
	<u-kumar1@...com>
Subject: [PATCH v6 0/2]  Add support for DSC and FEC for cadence MHDP8546 bridge

Hi all,

This patch series extends the Cadence MHDP8546 DisplayPort bridge
driver to support Display Stream Compression (DSC) and Forward Error
Correction (FEC).

DSC acts as an encoder block: when the sink reports DSC capability,
the DPI input stream to the MHDP8546 TX is compressed, and the sink
decodes the stream for display.

The first patch add the DSC module to the code.
The second patch implements the corresponding driver changes to enable
DSC and FEC when advertised by the sink and configured via DT.

Link: https://www.ti.com/lit/zip/spruil1
TRM File: SPRUIL_DRA829_TDA4VM_Technical Reference Manual.pdf 
(Figure 12-1115 and DSC related sections) 

Link to v5:
<https://lore.kernel.org/all/20250915103041.3891448-1-h-shenoy@ti.com/>

Changelog v5 -> v6:
-Drop binding patches, changes done in binding via fixes patch
<https://lore.kernel.org/all/20251203-caped-bullmastiff-from-jupiter-3dcaf3@quoll/>
-Split the implementation of dsc and adding support to driver parts of patch.
-Add a version check before attempting to read FEC capability.
-Reduce log level to debug for cdns_mhdp_fec_sink_support.
-Use the newer DPCD helpers that return 0 on success instead of size.
-No Need to Read Back DPCD.
-Optional Feature Messaging for FEC.
-Add FEC check before attempting DSC.
-Simplify initial lines calculation.
-Formatting issues in SOURCE_PIF_PKT_ALLOC_WR_EN_EN writel resolved.
-Use sizeof instead of magic number for pps_infoframe.
-Use forward declaration and remove redundant headers.
-Add DRM_DISPLAY_DSC_HELPER as dependency.

Link to v4: 
<https://lore.kernel.org/all/20250909054622.1439487-1-h-shenoy@ti.com>

Changelog v4 -> v5:
-Defining reg-names item list in iF conditional, added 
description for reg-names.
-Verified the bindings with cdns,mhdp8546 compatible.
-Add code for enabling DSC in bridge driver.
Log link-
<https://gist.github.com/h-shenoy/0318e2c6e7df539e6bdd39b77e5a8f05> 

Link to v3:
<https://lore.kernel.org/all/20250908054609.1113360-1-h-shenoy@ti.com/>

Changelog v3 -> v4:
-Remove maxItems as item list is mentioned for reg-names, resolves 
dt_bindings_check warning.
Log link- <https://gist.github.com/h-shenoy/5391ea514bb58a6cba3f39248d20916b>

Link to v2:
<https://lore.kernel.org/all/20250903111357.2605199-1-h-shenoy@ti.com/>
Changelog v2 --> v3:
-Update the name of dsc register block.
-Add the reg-name list in conditional based on compatible.

Link to v1:
<https://lore.kernel.org/all/9599e17c-96d5-448f-96a2-bbcfcc3657a2@ti.com/>


Swapnil Jakhade (2):
  drm/bridge: cdns-mhdp: Implement Display Stream Compression (DSC) for
    cdns-mhdp driver
  drm/bridge: cdns-mhdp8546: Add DSC support for Cadence MHDP8546 bridge

 drivers/gpu/drm/bridge/cadence/Kconfig        |   1 +
 drivers/gpu/drm/bridge/cadence/Makefile       |   2 +-
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 357 ++++++++-
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  69 ++
 .../drm/bridge/cadence/cdns-mhdp8546-dsc.c    | 718 ++++++++++++++++++
 .../drm/bridge/cadence/cdns-mhdp8546-dsc.h    | 284 +++++++
 6 files changed, 1409 insertions(+), 22 deletions(-)
 create mode 100644 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-dsc.c
 create mode 100644 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-dsc.h

-- 
2.34.1