Re: [Intel-gfx] [PATCH v5 00/15] drm/i915: HuC loading for DG2

["Winkler, Tomas" <tomas.winkler@intel.com>]

> On Wed, Sep 14, 2022 at 04:51:03PM +0000, Winkler, Tomas wrote:
> > >
> > > On DG2, HuC loading is performed by the GSC, via a PXP command. The
> > > load operation itself is relatively simple (just send a message to
> > > the GSC with the physical address of the HuC in LMEM), but there are
> > > timing changes that requires special attention. In particular, to
> > > send a PXP command we need to first export the GSC as an aux device
> > > and then wait for the mei-gsc and mei- pxp modules to start, which
> > > means that HuC load will complete after i915 load is complete. This
> > > means that there is a small window of time after i915 is registered
> > > and before HuC is loaded during which userspace could submit and/or
> > > check the HuC load status, although this is quite unlikely to happen (HuC
> is usually loaded before kernel init/resume completes).
> > > We've consulted with the media team in regards to how to handle this
> > > and they've asked us to stall all userspace VCS submission until HuC is
> loaded.
> > > Stalls are expected to be very rare (if any), due to the fact that
> > > HuC is usually loaded before kernel init/resume is completed.
> > >
> > > Timeouts are in place to ensure all submissions are unlocked in case
> > > something goes wrong. Since we need to monitor the status of the mei
> > > driver to know what's happening and when to time out, a notifier has
> > > been added so we get a callback when the status of the mei driver
> changes.
> > >
> > > Note that this series includes several mei patches that add support
> > > for sending the HuC loading command via mei-gsc. We plan to merge
> > > those patches through the drm tree because i915 is the sole user.
> > >
> > > v2: address review comments, Reporting HuC loading still in progress
> > > while we wait for mei-gsc init to complete, rebase on latest mei-gsc
> series.
> > >
> > > v3: fix cc list in mei patches.
> > >
> > > v4: update mei patches, fix includes, rebase on new FW fetch logic
> > > and merged mei-gsc support.
> > >
> > > v5: update mei patches
> >
> > Greg,  I hope I've addressed most of your comments.
> > Can you please check if the mei patches are in acceptable state or anything
> else can be improved with this series.  Appreciated.
> 
> These were sent 2 days ago, in the middle of a conference travel.
> Please relax, there's no special rush needed here, you know better.
Sure

> In the mean time, if you are just waiting for my review, please take the time
> to review other pending patches from other developers to help lighten the
> load on me, and other maintainers.
Fair enough, that's all I do every day anyway. 
Thanks
Tomas