[PATCH] drm/doc/rfc: Remove Xe's pre-merge plan

[Rodrigo Vivi]

The last TODO item here that was not marked as done was
the display portion, which came along with the pull-request.

So, now that Xe is part of drm-next and it includes the
display portion, let's entirely kill this RFC here.

Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Oded Gabbay <ogabbay at kernel.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 Documentation/gpu/rfc/xe.rst | 234 -----------------------------------
 1 file changed, 234 deletions(-)
 delete mode 100644 Documentation/gpu/rfc/xe.rst

diff --git a/Documentation/gpu/rfc/xe.rst b/Documentation/gpu/rfc/xe.rst
deleted file mode 100644
index 97cf87578f97..000000000000
--- a/Documentation/gpu/rfc/xe.rst
+++ /dev/null
@@ -1,234 +0,0 @@
-==========================
-Xe – Merge Acceptance Plan
-==========================
-Xe is a new driver for Intel GPUs that supports both integrated and
-discrete platforms starting with Tiger Lake (first Intel Xe Architecture).
-
-This document aims to establish a merge plan for the Xe, by writing down clear
-pre-merge goals, in order to avoid unnecessary delays.
-
-Xe – Overview
-=============
-The main motivation of Xe is to have a fresh base to work from that is
-unencumbered by older platforms, whilst also taking the opportunity to
-rearchitect our driver to increase sharing across the drm subsystem, both
-leveraging and allowing us to contribute more towards other shared components
-like TTM and drm/scheduler.
-
-This is also an opportunity to start from the beginning with a clean uAPI that is
-extensible by design and already aligned with the modern userspace needs. For
-this reason, the memory model is solely based on GPU Virtual Address space
-bind/unbind (‘VM_BIND’) of GEM buffer objects (BOs) and execution only supporting
-explicit synchronization. With persistent mapping across the execution, the
-userspace does not need to provide a list of all required mappings during each
-submission.
-
-The new driver leverages a lot from i915. As for display, the intent is to share
-the display code with the i915 driver so that there is maximum reuse there.
-
-As for the power management area, the goal is to have a much-simplified support
-for the system suspend states (S-states), PCI device suspend states (D-states),
-GPU/Render suspend states (R-states) and frequency management. It should leverage
-as much as possible all the existent PCI-subsystem infrastructure (pm and
-runtime_pm) and underlying firmware components such PCODE and GuC for the power
-states and frequency decisions.
-
-Repository:
-
-https://gitlab.freedesktop.org/drm/xe/kernel (branch drm-xe-next)
-
-Xe – Platforms
-==============
-Currently, Xe is already functional and has experimental support for multiple
-platforms starting from Tiger Lake, with initial support in userspace implemented
-in Mesa (for Iris and Anv, our OpenGL and Vulkan drivers), as well as in NEO
-(for OpenCL and Level0).
-
-During a transition period, platforms will be supported by both Xe and i915.
-However, the force_probe mechanism existent in both drivers will allow only one
-official and by-default probe at a given time.
-
-For instance, in order to probe a DG2 which PCI ID is 0x5690 by Xe instead of
-i915, the following set of parameters need to be used:
-
-```
-i915.force_probe=!5690 xe.force_probe=5690
-```
-
-In both drivers, the ‘.require_force_probe’ protection forces the user to use the
-force_probe parameter while the driver is under development. This protection is
-only removed when the support for the platform and the uAPI are stable. Stability
-which needs to be demonstrated by CI results.
-
-In order to avoid user space regressions, i915 will continue to support all the
-current platforms that are already out of this protection. Xe support will be
-forever experimental and dependent on the usage of force_probe for these
-platforms.
-
-When the time comes for Xe, the protection will be lifted on Xe and kept in i915.
-
-Xe – Pre-Merge Goals - Work-in-Progress
-=======================================
-
-Display integration with i915
------------------------------
-In order to share the display code with the i915 driver so that there is maximum
-reuse, the i915/display/ code is built twice, once for i915.ko and then for
-xe.ko. Currently, the i915/display code in Xe tree is polluted with many 'ifdefs'
-depending on the build target. The goal is to refactor both Xe and i915/display
-code simultaneously in order to get a clean result before they land upstream, so
-that display can already be part of the initial pull request towards drm-next.
-
-However, display code should not gate the acceptance of Xe in upstream. Xe
-patches will be refactored in a way that display code can be removed, if needed,
-from the first pull request of Xe towards drm-next. The expectation is that when
-both drivers are part of the drm-tip, the introduction of cleaner patches will be
-easier and speed up.
-
-Xe – uAPI high level overview
-=============================
-
-...Warning: To be done in follow up patches after/when/where the main consensus in various items are individually reached.
-
-Xe – Pre-Merge Goals - Completed
-================================
-
-Drm_exec
---------
-Helper to make dma_resv locking for a big number of buffers is getting removed in
-the drm_exec series proposed in https://patchwork.freedesktop.org/patch/524376/
-If that happens, Xe needs to change and incorporate the changes in the driver.
-The goal is to engage with the Community to understand if the best approach is to
-move that to the drivers that are using it or if we should keep the helpers in
-place waiting for Xe to get merged.
-
-This item ties into the GPUVA, VM_BIND, and even long-running compute support.
-
-As a key measurable result, we need to have a community consensus documented in
-this document and the Xe driver prepared for the changes, if necessary.
-
-Userptr integration and vm_bind
--------------------------------
-Different drivers implement different ways of dealing with execution of userptr.
-With multiple drivers currently introducing support to VM_BIND, the goal is to
-aim for a DRM consensus on what’s the best way to have that support. To some
-extent this is already getting addressed itself with the GPUVA where likely the
-userptr will be a GPUVA with a NULL GEM call VM bind directly on the userptr.
-However, there are more aspects around the rules for that and the usage of
-mmu_notifiers, locking and other aspects.
-
-This task here has the goal of introducing a documentation of the basic rules.
-
-The documentation *needs* to first live in this document (API session below) and
-then moved to another more specific document or at Xe level or at DRM level.
-
-Documentation should include:
-
- * The userptr part of the VM_BIND api.
-
- * Locking, including the page-faulting case.
-
- * O(1) complexity under VM_BIND.
-
-The document is now included in the drm documentation :doc:`here </gpu/drm-vm-bind-async>`.
-
-Some parts of userptr like mmu_notifiers should become GPUVA or DRM helpers when
-the second driver supporting VM_BIND+userptr appears. Details to be defined when
-the time comes.
-
-The DRM GPUVM helpers do not yet include the userptr parts, but discussions
-about implementing them are ongoing.
-
-ASYNC VM_BIND
--------------
-Although having a common DRM level IOCTL for VM_BIND is not a requirement to get
-Xe merged, it is mandatory to have a consensus with other drivers and Mesa.
-It needs to be clear how to handle async VM_BIND and interactions with userspace
-memory fences. Ideally with helper support so people don't get it wrong in all
-possible ways.
-
-As a key measurable result, the benefits of ASYNC VM_BIND and a discussion of
-various flavors, error handling and sample API suggestions are documented in
-:doc:`The ASYNC VM_BIND document </gpu/drm-vm-bind-async>`.
-
-Drm_scheduler
--------------
-Xe primarily uses Firmware based scheduling (GuC FW). However, it will use
-drm_scheduler as the scheduler ‘frontend’ for userspace submission in order to
-resolve syncobj and dma-buf implicit sync dependencies. However, drm_scheduler is
-not yet prepared to handle the 1-to-1 relationship between drm_gpu_scheduler and
-drm_sched_entity.
-
-Deeper changes to drm_scheduler should *not* be required to get Xe accepted, but
-some consensus needs to be reached between Xe and other community drivers that
-could also benefit from this work, for coupling FW based/assisted submission such
-as the ARM’s new Mali GPU driver, and others.
-
-As a key measurable result, the patch series introducing Xe itself shall not
-depend on any other patch touching drm_scheduler itself that was not yet merged
-through drm-misc. This, by itself, already includes the reach of an agreement for
-uniform 1 to 1 relationship implementation / usage across drivers.
-
-Long running compute: minimal data structure/scaffolding
---------------------------------------------------------
-The generic scheduler code needs to include the handling of endless compute
-contexts, with the minimal scaffolding for preempt-ctx fences (probably on the
-drm_sched_entity) and making sure drm_scheduler can cope with the lack of job
-completion fence.
-
-The goal is to achieve a consensus ahead of Xe initial pull-request, ideally with
-this minimal drm/scheduler work, if needed, merged to drm-misc in a way that any
-drm driver, including Xe, could re-use and add their own individual needs on top
-in a next stage. However, this should not block the initial merge.
-
-Dev_coredump
-------------
-
-Xe needs to align with other drivers on the way that the error states are
-dumped, avoiding a Xe only error_state solution. The goal is to use devcoredump
-infrastructure to report error states, since it produces a standardized way
-by exposing a virtual and temporary /sys/class/devcoredump device.
-
-As the key measurable result, Xe driver needs to provide GPU snapshots captured
-at hang time through devcoredump, but without depending on any core modification
-of devcoredump infrastructure itself.
-
-Later, when we are in-tree, the goal is to collaborate with devcoredump
-infrastructure with overall possible improvements, like multiple file support
-for better organization of the dumps, snapshot support, dmesg extra print,
-and whatever may make sense and help the overall infrastructure.
-
-DRM_VM_BIND
------------
-Nouveau, and Xe are all implementing ‘VM_BIND’ and new ‘Exec’ uAPIs in order to
-fulfill the needs of the modern uAPI. Xe merge should *not* be blocked on the
-development of a common new drm_infrastructure. However, the Xe team needs to
-engage with the community to explore the options of a common API.
-
-As a key measurable result, the DRM_VM_BIND needs to be documented in this file
-below, or this entire block deleted if the consensus is for independent drivers
-vm_bind ioctls.
-
-Although having a common DRM level IOCTL for VM_BIND is not a requirement to get
-Xe merged, it is mandatory to enforce the overall locking scheme for all major
-structs and list (so vm and vma). So, a consensus is needed, and possibly some
-common helpers. If helpers are needed, they should be also documented in this
-document.
-
-GPU VA
-------
-Two main goals of Xe are meeting together here:
-
-1) Have an uAPI that aligns with modern UMD needs.
-
-2) Early upstream engagement.
-
-RedHat engineers working on Nouveau proposed a new DRM feature to handle keeping
-track of GPU virtual address mappings. This is still not merged upstream, but
-this aligns very well with our goals and with our VM_BIND. The engagement with
-upstream and the port of Xe towards GPUVA is already ongoing.
-
-As a key measurable result, Xe needs to be aligned with the GPU VA and working in
-our tree. Missing Nouveau patches should *not* block Xe and any needed GPUVA
-related patch should be independent and present on dri-devel or acked by
-maintainers to go along with the first Xe pull request towards drm-next.
-- 
2.43.0