Re: [Intel-gfx] [PATCH v6 5/8] drm/i915/pxp: Add ARB session creation and cleanup

["Teres Alexis, Alan Previn" <alan.previn.teres.alexis@intel.com>]

On Wed, 2023-03-29 at 08:43 +0100, Tvrtko Ursulin wrote:
> On 28/03/2023 18:52, Rodrigo Vivi wrote:
> > On Tue, Mar 28, 2023 at 05:01:36PM +0000, Teres Alexis, Alan Previn wrote:
> > > On Mon, 2023-03-27 at 17:15 +0100, Tvrtko Ursulin wrote:
> > > 
alan:snip
> How will the context create path look like on those platforms:
> 
> 1. Block, then potentially error out if the full initialization failed.
> 2. Error out "in progress" while initializing, error out "something 
> else" if initialization failed.
> 
alan:i was thinking of taking a page from huc-authentication's get-param where we could return different values based on startup progress - in all cases we never block:
 1. we dont support it in hw/kernel (i.e. not pxp in device-info or not enough CONFIG_foo - reusing intel_pxp_is_supported?)
 2. we support it in kernel but internal dependencies are still in progress (i.e. we have not yet completed huc-loading/huc-authen/proxy-init - UAPI spec should include how many
max seconds delay per platform)
 3. we support it in kernel but internal dependencies failed (i.e. we know huc-load/authent. failed ... or we know proxy-init failed).
 4. we support it in kernel but platform has no support (at this stage we actually attempt to create a PXP context or create the arb-session from inside i915-get-param but we ended
up a PXP fw error indicating select list of failures such as fusing / BIOS-config / wrong-version.
 0. we support it completely i.e. step 4's attempt to create active PXP session succeeded

I want to differentiate 3 and 4 (as opposed to return x-means-ENODEV) because i have am sure it will save debug time when facing customer issues.
Ofc we will have to optimize the checking sequences above but at #4, we would be creating a session which might take up to ~200 milisecs for the round trip response from fw.
We could store a flag in i915-pxp-internal-struct to indicate if we ever did succeed a pxp creation after a fresh boot ... intel_pxp_is_ready_for_active()? 
... true only if we ever did allocate a slot successfully at least once since boot.
This also ensure mesa init will return almost immediately except at the first time when hitting #4.