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49b2dfc081
We don't currently have any kind of real acceleration on Ampere GPUs, but the TTM memcpy() fallback paths aren't really designed to handle copies between different devices, such as on Optimus systems, and result in a kernel OOPS. A few options were investigated to try and fix this, but didn't work out, and likely would have resulted in a very unpleasant experience for users anyway. This commit adds just enough support for setting up a single channel connected to a copy engine, which the kernel can use to accelerate the buffer copies between devices. Userspace has no access to this incomplete channel support, but it's suitable for TTM's needs. A more complete implementation of host(fifo) for Ampere GPUs is in the works, but the required changes are far too invasive that they would be unsuitable to backport to fix this issue on current kernels. v2: fix GPFIFO length in RAMFC (reported by Karol) Signed-off-by: Ben Skeggs <bskeggs@redhat.com> Cc: Lyude Paul <lyude@redhat.com> Cc: Karol Herbst <kherbst@redhat.com> Cc: <stable@vger.kernel.org> # v5.12+ Reviewed-by: Karol Herbst <kherbst@redhat.com> Tested-by: Karol Herbst <kherbst@redhat.com> Signed-off-by: Karol Herbst <kherbst@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210916220406.666454-1-skeggsb@gmail.com Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.