27536e0327
Given that HuC load is delayed on DG2, this patch adds support for a fence that can be used to wait for load completion. No waiters are added in this patch (they're coming up in the next one), to keep the focus of the patch on the tracking logic. The full HuC loading flow on boot DG2 is as follows: 1) i915 exports the GSC as an aux device; 2) the mei-gsc driver is loaded on the aux device; 3) the mei-pxp component is loaded; 4) mei-pxp calls back into i915 and we load the HuC. Between steps 1 and 2 there can be several seconds of gap, mainly due to the kernel doing other work during the boot. The resume flow is slightly different, because we don't need to re-expose or re-probe the aux device, so we go directly to step 3 once i915 and mei-gsc have completed their resume flow. Here's an example of the boot timing, captured with some logs added to i915: [ 17.908307] [drm] adding GSC device [ 17.915717] [drm] i915 probe done [ 22.282917] [drm] mei-gsc bound [ 22.938153] [drm] HuC authenticated Also to note is that if something goes wrong during GSC HW init the mei-gsc driver will still bind, but steps 3 and 4 will not happen. The status tracking is done by registering a bus_notifier to receive a callback when the mei-gsc driver binds, with a large enough timeout to account for delays. Once mei-gsc is bound, we switch to a smaller timeout to wait for the mei-pxp component to load. The fence is signalled on HuC load complete or if anything goes wrong in any of the tracking steps. Timeout are enforced via hrtimer callbacks. v2: fix includes (Jani) v5: gsc_notifier() remove unneeded () Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220928004145.745803-12-daniele.ceraolospurio@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.