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Alessio Belle 9cd74f9353
drm/imagination: Count paired job fence as dependency in prepare_job()
The DRM scheduler's prepare_job() callback counts the remaining
non-signaled native dependencies for a job, preventing job submission
until those (plus job data and fence update) can fit in the job queue's
CCCB.

This means checking which dependencies can be waited upon in the
firmware, i.e. whether they are backed by a UFO object, i.e. whether
their drm_sched_fence::parent has been assigned to a
pvr_queue_fence::base fence. That happens when the job owning the fence
is submitted to the firmware.

Paired geometry and fragment jobs are submitted at the same time, which
means the dependency between them can't be checked this way before
submission.

Update job_count_remaining_native_deps() to take into account the
dependency between paired jobs.

This fixes cases where prepare_job() underestimated the space left in
an almost full fragment CCCB, wrongly unblocking run_job(), which then
returned early without writing the full sequence of commands to the
CCCB.

The above lead to kernel warnings such as the following and potentially
job timeouts (depending on waiters on the missing commands):

  [  375.702979] WARNING: drivers/gpu/drm/imagination/pvr_cccb.c:178 at pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr], CPU#1: kworker/u16:3/47
  [  375.703160] Modules linked in:
  [  375.703571] CPU: 1 UID: 0 PID: 47 Comm: kworker/u16:3 Tainted: G        W           7.0.0-rc2-g817eb6b11ad5 #40 PREEMPT
  [  375.703613] Tainted: [W]=WARN
  [  375.703627] Hardware name: Texas Instruments AM625 SK (DT)
  [  375.703645] Workqueue: powervr-sched drm_sched_run_job_work [gpu_sched]
  [  375.703741] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  [  375.703764] pc : pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr]
  [  375.703847] lr : pvr_queue_submit_job_to_cccb+0x578/0xa70 [powervr]
  [  375.703921] sp : ffff800084a97650
  [  375.703934] x29: ffff800084a97740 x28: 0000000000000958 x27: ffff80008565d000
  [  375.703979] x26: 0000000000000030 x25: ffff800084a97680 x24: 0000000000001000
  [  375.704017] x23: ffff800084a97820 x22: 1ffff00010952ecc x21: 0000000000000008
  [  375.704056] x20: 00000000000006a8 x19: ffff00002ff7da88 x18: 0000000000000000
  [  375.704093] x17: 0000000020020000 x16: 0000000000020000 x15: 0000000000000000
  [  375.704132] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
  [  375.704168] x11: 000000000000f2f2 x10: 00000000f3000000 x9 : 00000000f3f3f3f3
  [  375.704206] x8 : 00000000f2f2f200 x7 : ffff700010952ecc x6 : 0000000000000008
  [  375.704243] x5 : 0000000000000000 x4 : 1ffff00010acba00 x3 : 0000000000000000
  [  375.704279] x2 : 0000000000000007 x1 : 0000000000000fff x0 : 000000000000002f
  [  375.704317] Call trace:
  [  375.704331]  pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr] (P)
  [  375.704411]  pvr_queue_submit_job_to_cccb+0x578/0xa70 [powervr]
  [  375.704487]  pvr_queue_run_job+0x3a4/0x990 [powervr]
  [  375.704562]  drm_sched_run_job_work+0x580/0xd48 [gpu_sched]
  [  375.704623]  process_one_work+0x520/0x1288
  [  375.704658]  worker_thread+0x3f0/0xb3c
  [  375.704680]  kthread+0x334/0x3d8
  [  375.704706]  ret_from_fork+0x10/0x20
  [  375.704736] ---[ end trace 0000000000000000 ]---

Fixes: eaf01ee5ba ("drm/imagination: Implement job submission and scheduling")
Cc: stable@vger.kernel.org
Signed-off-by: Alessio Belle <alessio.belle@imgtec.com>
Reviewed-by: Brajesh Gupta <brajesh.gupta@imgtec.com>
Link: https://patch.msgid.link/20260330-job-submission-fixes-cleanup-v1-1-7de8c09cef8c@imgtec.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
2026-04-08 11:17:12 +01:00
arch RISC-V updates for v7.0-rc7 2026-04-05 14:43:47 -07:00
block block-7.0-20260305 2026-03-06 08:36:18 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto This push contains the following changes: 2026-04-02 17:29:48 -07:00
Documentation Merge drm/drm-next into drm-misc-next 2026-04-08 10:09:43 +02:00
drivers drm/imagination: Count paired job fence as dependency in prepare_job() 2026-04-08 11:17:12 +01:00
fs mm: add gpu active/reclaim per-node stat counters (v2) 2026-04-08 06:52:47 +10:00
include Merge drm/drm-next into drm-misc-next 2026-04-08 10:09:43 +02:00
init hardening fixes for v7.0-rc6 2026-03-25 14:47:18 -07:00
io_uring io_uring-7.0-20260403 2026-04-03 11:58:04 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Misc scheduler fixes: 2026-04-05 13:45:37 -07:00
lib Crypto library fixes for v7.0-rc7 2026-03-30 13:40:48 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm ttm/pool: port to list_lru. (v2) 2026-04-08 06:52:47 +10:00
net bpf-fixes 2026-04-02 18:59:56 -07:00
rust DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
samples DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
scripts DRM Rust changes for v7.1-rc1 2026-04-01 07:32:05 +10:00
security Landlock fix for v7.0-rc6 2026-03-26 12:03:37 -07:00
sound USB/Thunderbolt fixes for 7.0-rc7 2026-04-05 10:00:26 -07:00
tools RISC-V updates for v7.0-rc7 2026-04-05 14:43:47 -07:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM generic changes for 7.0 2026-03-11 18:01:55 +01:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Merge tag 'drm-intel-next-2026-03-30' of https://gitlab.freedesktop.org/drm/i915/kernel into drm-next 2026-03-31 16:38:50 +10:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: remove Thomas Falcon from IBM ibmvnic 2026-03-05 07:35:45 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge tag 'drm-msm-next-2026-04-02' of https://gitlab.freedesktop.org/drm/msm into drm-next 2026-04-03 18:57:00 +10:00
Makefile Linux 7.0-rc7 2026-04-05 15:26:23 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

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
* AI Coding Assistant - LLMs and AI-powered development tools


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

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


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