.. kernel-doc:: drivers/gpu/drm/vkms/vkms_drv.c
:doc: vkms (Virtual Kernel Modesetting)
+Setup
+=====
+
+The VKMS driver can be setup with the following steps:
+
+To check if VKMS is loaded, run::
+
+ lsmod | grep vkms
+
+This should list the VKMS driver. If no output is obtained, then
+you need to enable and/or load the VKMS driver.
+Ensure that the VKMS driver has been set as a loadable module in your
+kernel config file. Do::
+
+ make nconfig
+
+ Go to `Device Drivers> Graphics support`
+
+ Enable `Virtual KMS (EXPERIMENTAL)`
+
+Compile and build the kernel for the changes to get reflected.
+Now, to load the driver, use::
+
+ sudo modprobe vkms
+
+On running the lsmod command now, the VKMS driver will appear listed.
+You can also observe the driver being loaded in the dmesg logs.
+
+The VKMS driver has optional features to simulate different kinds of hardware,
+which are exposed as module options. You can use the `modinfo` command
+to see the module options for vkms::
+
+ modinfo vkms
+
+Module options are helpful when testing, and enabling modules
+can be done while loading vkms. For example, to load vkms with cursor enabled,
+use::
+
+ sudo modprobe vkms enable_cursor=1
+
+To disable the driver, use ::
+
+ sudo modprobe -r vkms
+
+Testing With IGT
+================
+
+The IGT GPU Tools is a test suite used specifically for debugging and
+development of the DRM drivers.
+The IGT Tools can be installed from
+`here <https://gitlab.freedesktop.org/drm/igt-gpu-tools>`_ .
+
+The tests need to be run without a compositor, so you need to switch to text
+only mode. You can do this by::
+
+ sudo systemctl isolate multi-user.target
+
+To return to graphical mode, do::
+
+ sudo systemctl isolate graphical.target
+
+Once you are in text only mode, you can run tests using the --device switch
+or IGT_DEVICE variable to specify the device filter for the driver we want
+to test. IGT_DEVICE can also be used with the run-test.sh script to run the
+tests for a specific driver::
+
+ sudo ./build/tests/<name of test> --device "sys:/sys/devices/platform/vkms"
+ sudo IGT_DEVICE="sys:/sys/devices/platform/vkms" ./build/tests/<name of test>
+ sudo IGT_DEVICE="sys:/sys/devices/platform/vkms" ./scripts/run-tests.sh -t <name of test>
+
+For example, to test the functionality of the writeback library,
+we can run the kms_writeback test::
+
+ sudo ./build/tests/kms_writeback --device "sys:/sys/devices/platform/vkms"
+ sudo IGT_DEVICE="sys:/sys/devices/platform/vkms" ./build/tests/kms_writeback
+ sudo IGT_DEVICE="sys:/sys/devices/platform/vkms" ./scripts/run-tests.sh -t kms_writeback
+
+You can also run subtests if you do not want to run the entire test::
+
+ sudo ./build/tests/kms_flip --run-subtest basic-plain-flip --device "sys:/sys/devices/platform/vkms"
+ sudo IGT_DEVICE="sys:/sys/devices/platform/vkms" ./build/tests/kms_flip --run-subtest basic-plain-flip
+
TODO
====
IGT better support
------------------
-- Investigate: (1) test cases on kms_plane that are failing due to timeout on
- capturing CRC; (2) when running kms_flip test cases in sequence, some
- successful individual test cases are failing randomly.
+Debugging:
+
+- kms_plane: some test cases are failing due to timeout on capturing CRC;
+
+- kms_flip: when running test cases in sequence, some successful individual
+ test cases are failing randomly; when individually, some successful test
+ cases display in the log the following error::
+
+ [drm:vkms_prepare_fb [vkms]] ERROR vmap failed: -4
+
+Virtual hardware (vblank-less) mode:
- VKMS already has support for vblanks simulated via hrtimers, which can be
tested with kms_flip test; in some way, we can say that VKMS already mimics
There's lots of plane features we could add support for:
-- Real overlay planes, not just cursor.
+- Multiple overlay planes. [Good to get started]
+
+- Clearing primary plane: clear primary plane before plane composition (at the
+ start) for correctness of pixel blend ops. It also guarantees alpha channel
+ is cleared in the target buffer for stable crc. [Good to get started]
+
+- ARGB format on primary plane: blend the primary plane into background with
+ translucent alpha.
+
+- Support when the primary plane isn't exactly matching the output size: blend
+ the primary plane into the black background.
- Full alpha blending on all planes.
cursor api).
For all of these, we also want to review the igt test coverage and make sure
-all relevant igt testcases work on vkms.
-
-Prime Buffer Sharing
---------------------
-
-- Syzbot report - WARNING in vkms_gem_free_object:
- https://syzkaller.appspot.com/bug?extid=e7ad70d406e74d8fc9d0
+all relevant igt testcases work on vkms. They are good options for internship
+project.
Runtime Configuration
---------------------
the refresh rate.
The currently proposed solution is to expose vkms configuration through
-configfs. All existing module options should be supported through configfs
+configfs. All existing module options should be supported through configfs
too.
Writeback support
- The writeback and CRC capture operations share the use of composer_enabled
boolean to ensure vblanks. Probably, when these operations work together,
composer_enabled needs to refcounting the composer state to proper work.
+ [Good to get started]
- Add support for cloned writeback outputs and related test cases using a
cloned output in the IGT kms_writeback.
projects / linux-2.6-microblaze.git / blobdiff