Currently, each process holding an open TegraDRM channel reserves
for itself one of the limited number of hardware memory contexts.
Attempting to allocate a channel when all contexts are in use
results in failure.
While we cannot have more contexts than the hardware supports in
active use, idle channels don't necessarily need to have a backing
memory context. As such, in this patch, we add another layer
to allow hardware memory contexts to be "stolen away" by channels
that are in active use, from idle processes.
The way this is implemented, is by keeping track of memory
mappings on each abstracted memory context. If we need to
steal that memory context's backing hardware context, we unmap
everything from it and give it away. When that abstracted
memory context is needed again (re-activated), we attempt
to allocate or steal another hardware context and re-map
the previously unmapped buffers.
Unfortunately, this means additional overhead and unpredictability
at submit time. Submit can fail if we cannot re-allocate a
backing memory context. Future work includes a provision for
un-stealable backing hardware memory contexts for processes
requiring more determinism, as well as optimization and cosmetic
improvements.
Bug 4403250
Bug 4399310
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Change-Id: I3d13e3476f1bff3c4757152254496cddaaafd76a
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3058905
Reviewed-by: Santosh BS <santoshb@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3227749
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
Tested-by: Dane Liu <danel@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Add the upstream tegra-drm driver with the 'Host1x/Tegra UAPI' series
[0] applied. This driver will be built as an external module for testing
and development with upstream Linux kernels.
The following modifications have been made to the series posted upstream
1. Update the Makefile to always build the driver as a module
2. Always enable the tegra_drm_ioctl_xxx in the tegra_drm_ioctls and
remove the dependency on CONFIG_DRM_TEGRA_STAGING.
3. Rename the include/uapi/drm/tegra_drm.h to
include/uapi/drm/tegra_drm_next.h to avoid conflicts with upstream
headers when building as an external module.
5. Rename the module that is built to be tegra-drm-next.ko instead of
tegra-drm.ko to avoid any depmod conflicts with the upstream driver.
[0] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=215770
Bug 3156385
Change-Id: I19206f989325c9c6ff3c2b9301d964140d52234f
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2435802
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
