[Intel-gfx] [PATCH 1/2] drm/i915/guc: always use Command Transport Buffers

[Daniele Ceraolo Spurio]

On 6/5/19 8:20 AM, Michal Wajdeczko wrote:
> On Tue, 04 Jun 2019 22:29:20 +0200, Daniele Ceraolo Spurio 
> <daniele.ceraolospurio at intel.com> wrote:
> 
>> Now that we've moved the gen9 guc blobs to version 32 we have CTB
>> support on all gens, so no need to restrict the usage to gen11+.
>> Note that mmio communication is still required for CTB initialization.
> 
> s/gen9/Gen9
> s/guc/GuC
> s/gen11/Gen11
> s/mmio/MMIO
> 
>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> ---
> 
> For simple enable_guc=2 mode (HuC auth only) use of CTB might be
> viewed as small overkill, but I assume fw prefers that way.
> 

Spoiler alert: I've heard that since huc auth is currently a multi-step 
process within guc/HW, to make debugging HuC loading issues easier the 
guc devs plan to add an extra G2H after the completion of the first 
step, which will only be supported via CTB. This was not the reason why 
I sent this patch (I'm not even sure if the plan is confirmed), but I 
guess it helps reinforcing the argument for using CTB with enable_guc=2.

Daniele

> With above commit message nits,
> Reviewed-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>