631b117ea8
The display engine does not snoop the caches so we should mark the DSB command buffer as I915_CACHE_NONE. i915_gem_object_create_internal() always gives us I915_CACHE_LLC on LLC platforms. And to make things 100% correct we should also clflush at the end, if necessary. Note that currently this is a non-issue as we always write the command buffer through a WC mapping, so a cache flush is not actually needed. But we might actually want to consider a WB mapping since we also end up reading from the command buffer (in the indexed reg write handling). Either that or we should do something else to avoid those reads (might actually be even more sensible on DGFX since we end up reading over PCIe). But we should measure the overhead first... Anyways, no real harm in adding the belts and suspenders here so that the code will work correctly regardless of how we map the buffer. If we do get a WC mapping (as we request) i915_gem_object_flush_map() will be a nop. Well, apart form a wmb() which may just flush the WC buffer a bit earlier than would otherwise happen (at the latest the mmio accesses would trigger the WC flush). Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20231009132204.15098-2-ville.syrjala@linux.intel.com Reviewed-by: Uma Shankar <uma.shankar@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.