From: "André Almeida" <andrealmeid@igalia.com>
To: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Cc: kernel-dev@igalia.com, alexander.deucher@amd.com,
christian.koenig@amd.com, pierre-eric.pelloux-prayer@amd.com,
"Simon Ser" <contact@emersion.fr>,
"Rob Clark" <robdclark@gmail.com>,
"Pekka Paalanen" <ppaalanen@gmail.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Daniel Stone" <daniel@fooishbar.org>,
"'Marek Olšák'" <maraeo@gmail.com>,
"Dave Airlie" <airlied@gmail.com>,
"Michel Dänzer" <michel.daenzer@mailbox.org>,
"Samuel Pitoiset" <samuel.pitoiset@gmail.com>,
"Timur Kristóf" <timur.kristof@gmail.com>,
"Bas Nieuwenhuizen" <bas@basnieuwenhuizen.nl>,
"André Almeida" <andrealmeid@igalia.com>
Subject: [RFC PATCH v3 1/4] drm/doc: Document DRM device reset expectations
Date: Tue, 20 Jun 2023 21:57:16 -0300 [thread overview]
Message-ID: <20230621005719.836857-2-andrealmeid@igalia.com> (raw)
In-Reply-To: <20230621005719.836857-1-andrealmeid@igalia.com>
Create a section that specifies how to deal with DRM device resets for
kernel and userspace drivers.
Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
Documentation/gpu/drm-uapi.rst | 65 ++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
index 65fb3036a580..da4f8a694d8d 100644
--- a/Documentation/gpu/drm-uapi.rst
+++ b/Documentation/gpu/drm-uapi.rst
@@ -285,6 +285,71 @@ for GPU1 and GPU2 from different vendors, and a third handler for
mmapped regular files. Threads cause additional pain with signal
handling as well.
+Device reset
+============
+
+The GPU stack is really complex and is prone to errors, from hardware bugs,
+faulty applications and everything in between the many layers. To recover
+from this kind of state, sometimes is needed to reset the device. This section
+describes what's the expectations for DRM and usermode drivers when a device
+resets and how to propagate the reset status.
+
+Kernel Mode Driver
+------------------
+
+The KMD is responsible for checking if the device needs a reset, and to perform
+it as needed. Usually a hung is detected when a job gets stuck executing. KMD
+then update it's internal reset tracking to be ready when userspace asks the
+kernel about reset information. Drivers should implement the DRM_IOCTL_GET_RESET
+for that.
+
+User Mode Driver
+----------------
+
+The UMD should check before submitting new commands to the KMD if the device has
+been reset, and this can be checked more often if it requires to. The
+DRM_IOCTL_GET_RESET is the default interface for those kind of checks. After
+detecting a reset, UMD will then proceed to report it to the application using
+the appropriated API error code, as explained in the bellow section about
+robustness.
+
+Robustness
+----------
+
+The only way to try to keep an application working after a reset is if it
+complies with the robustness aspects of the graphical API that is using.
+
+Graphical APIs provide ways to application to deal with device resets. However,
+there's no guarantee that the app will be correctly using such features, and UMD
+can implement policies to close the app if it's a repeating offender, likely in
+a broken loop. This is done to ensure that it doesn't keeps blocking the user
+interface to be correctly displayed.
+
+OpenGL
+~~~~~~
+
+Apps using OpenGL can rely on ``GL_ARB_robustness`` to be robust. This extension
+tells if a reset has happened, and if so, all the context state is considered
+lost and the app proceeds by creating new ones. If robustness isn't in use, UMD
+will terminate the app when a reset is detected, giving that the contexts are
+lost and the app won't be able to figure this out and recreate the contexts.
+
+Vulkan
+~~~~~~
+
+Apps using Vulkan should check for ``VK_ERROR_DEVICE_LOST`` for submissions.
+This error code means, among other things, that a device reset has happened and
+it needs to recreate the contexts to keep going.
+
+Reporting resets causes
+-----------------------
+
+Apart from propagating the reset through the stack so apps can recover, it's
+really useful for driver developers to learn more about what caused the reset in
+first place. DRM devices should make use of devcoredump to store relevant
+information about the reset, so this information can be added to user bug
+reports.
+
.. _drm_driver_ioctl:
IOCTL Support on Device Nodes
--
2.41.0
next prev parent reply other threads:[~2023-06-21 0:58 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 0:57 [RFC PATCH v3 0/4] drm: Standardize device reset notification André Almeida
2023-06-21 0:57 ` André Almeida [this message]
2023-06-21 7:58 ` [RFC PATCH v3 1/4] drm/doc: Document DRM device reset expectations Pekka Paalanen
2023-06-21 16:28 ` André Almeida
2023-06-22 8:12 ` Pekka Paalanen
2023-06-26 16:15 ` André Almeida
2023-06-21 0:57 ` [RFC PATCH v3 2/4] drm: Create DRM_IOCTL_GET_RESET André Almeida
2023-06-21 8:09 ` Pekka Paalanen
2023-06-21 16:33 ` André Almeida
2023-06-22 8:22 ` Pekka Paalanen
2023-06-22 9:59 ` Christian König
2023-06-21 0:57 ` [RFC PATCH v3 3/4] drm/amdgpu: Implement DRM_IOCTL_GET_RESET André Almeida
2023-06-21 7:40 ` Christian König
2023-06-21 16:38 ` André Almeida
2023-06-22 7:45 ` Christian König
2023-06-21 0:57 ` [RFC PATCH v3 4/4] drm/i915: " André Almeida
2023-06-21 7:38 ` Jani Nikula
2023-06-21 7:42 ` [RFC PATCH v3 0/4] drm: Standardize device reset notification Christian König
2023-06-21 15:06 ` André Almeida
2023-06-21 15:09 ` Christian König
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