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By adjusting the order of link training and relocating it to HPD,
link training can identify the usability of each lane in the current link.
It also supports handling signal instability and weakness due to
environmental issues, enabling the acquisition of a stable bandwidth
for the current link. Subsequently, DP work can proceed based on
the actual maximum bandwidth.
It should training in the hpd event thread.
Check the mode with lane count and link rate of training.
If we're eDP and capabilities were already parsed we can skip
reading again because eDP panels aren't hotpluggable hence the
caps and training information won't ever change in a boot life
Therefore, bridge typec judgment is required for edp training in
atomic_enable function.
`mtk_dp_parse_capabilities` is related to DP training, it is
used in `mtk_dp_hpd_event_thread` before DP training, and then only
used by eDP when read edid.
-Modify part of in `mtk_dp_bridge_atomic_disable`
if (mtk_dp->train_info.cable_plugged_in) {
drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
usleep_range(2000, 3000);
}
/* power off aux */
mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
DP_PWR_STATE_BANDGAP_TPLL,
DP_PWR_STATE_MASK);
-Modify part of in `mtk_dp_aux_panel_poweron(mtk_dp, false);`
if (pwron) {
....
} else {
/* power off panel */
drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
usleep_range(2000, 3000);
/* power off aux */
mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
DP_PWR_STATE_BANDGAP_TPLL,
DP_PWR_STATE_MASK);
}
The `mtk_dp_aux_panel_poweron` function fails to align.
Within the `mtk_dp_hpd_event_thread`, if DP is disconnected,
the `mtk_dp_aux_panel_poweron` function will write from `aux`
to `DPRX`, causing a failure and thus preventing symmetry.
This shows the current timings after the DP cable is plugged in,
as well as the modified timings.
current timings: Fix timings:
mtk_dp_hpd_event_thread() mtk_dp_hpd_event_thread()
(including DP link training)
| |
... ...
mtk_dp_bridge_mode_valid() mtk_dp_bridge_mode_valid()
|
... ...
mtk_dp_bridge_atomic_check() mtk_dp_bridge_atomic_check()
|
... ...
mtk_dp_bridge_atomic_enable() mtk_dp_bridge_atomic_enable()
(including DP link training)
PS:
1. "..." represents ommited steps;
2. `mtk_dp_bridge_mode_valid()` calculates the bandwidth using the
current lane count and link rate, and then filters each mode to
determine if it supports returning a status.
3. In the `drm_display_mode_to_videomode(&crtc_state->adjusted_mode,
&mtk_dp->info.vm);` function, within the `mtk_dp_bridge_atomic_check()`
function, `adjusted_mode` sets the currently selected display mode for
the DRM.
4. DP link training tests the signal conditions of the link between
DPTX and DPRX, and selects the lane count and link rate that meet
the signal conditions.
5. For example, the platform support DP 4lane 5.4G,
but panel A support DP 2lane 5.4G.
This is a time sequence:
a).Plug in panel A. According to the platform, it can output 4K60Hz.
b).Timing mode set 4K 60Hz(Including in mtk_dp_bridge_atomic_check
function).
c).Atomic enable(Based on panel A ability, training pass 2lane
5.4G).
d).Finally, due to 2lane 5.4G bandwidth limitation, the platform
cannot output 4K 60Hz, resulting in a black sreen.
If apply this patch.
a).Plug in panel A.
b).Training pass 2lane 5.4G
c).Timing mode set 2K 60Hz(Based on the 2lane 5.4G bandwidth limit
and including in mtk_dp_bridge_atomic_che
Signed-off-by: Liankun Yang <liankun.yang@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20251223061755.7717-1-liankun.yang@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
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| ipc | ||
| kernel | ||
| lib | ||
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| .cocciconfig | ||
| .editorconfig | ||
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| .gitattributes | ||
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| COPYING | ||
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| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst