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[Why]
Regression of commit 72fef4980d ("drm/amdgpu: Remove writing GRBM_GFX_CNTL in RLCG interface under SRIOV") on GFX9.
According to GFX9 VF using different method to access GC registers including MMIO(direct) and RLCG(indirect),
removing GRBM_GFX_* writing would make PIPE/ME/VM/QUEUE selection chaos leading to some OCL benchmark failure.
For example,
using RLCG interface to program GRBM_GFX_CNTL/INDEX for selecting MEC(actually the value is only in scratch2/3),
then using MMIO directly program a MEC register in VF driver.
The register programming are invalid due to GC switched to incorrect ME.
[How]
With checking RLCG accessing flag, keep writing GRBM_GFX_* as a legacy way.
But it is still skipped on GFX10+ to avoid violation occurrence.
Signed-off-by: Yifan Zha <Yifan.Zha@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.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.