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c84c9029d7
Despite what I think the prm recommends, commitf2253bd985("drm/i915/ringbuffer: EMIT_INVALIDATE after switch context") turned out to be a huge mistake when enabling Ironlake contexts as the GPU would hang on either a MI_FLUSH or PIPE_CONTROL immediately following the MI_SET_CONTEXT of an active mesa context (more vanilla contexts, e.g. simple rendercopies with igt, do not suffer). Ville found the following clue, "[DevCTG+]: For the invalidate operation of the pipe control, the following pointers are affected. The invalidate operation affects the restore of these packets. If the pipe control invalidate operation is completed before the context save, the indirect pointers will not be restored from memory. 1. Pipeline State Pointer 2. Media State Pointer 3. Constant Buffer Packet" which suggests by us emitting the INVALIDATE prior to the MI_SET_CONTEXT, we prevent the context-restore from chasing the dangling pointers within the image, and explains why this likely prevents the GPU hang. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190419111749.3910-1-chris@chris-wilson.co.uk (cherry picked from commit928f8f4231in drm-intel-next) Cc: stable@vger.kernel.org Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111014 Fixes:f2253bd985("drm/i915/ringbuffer: EMIT_INVALIDATE after switch context") Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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.