[Intel-gfx] [PATCH] drm/i915/huc: Fix error reported by I915_PARAM_HUC_STATUS

[Michal Wajdeczko]

On Thu, 23 Jan 2020 16:02:17 +0100, Chris Wilson  
<chris at chris-wilson.co.uk> wrote:

> Quoting Daniele Ceraolo Spurio (2020-01-22 23:52:33)
>>
>>
>> On 1/22/20 11:48 AM, Michal Wajdeczko wrote:
>> >  From commit 84b1ca2f0e68 ("drm/i915/uc: prefer intel_gt over i915
>> > in GuC/HuC paths") we stopped using HUC_STATUS error -ENODEV only
>> > to indicate lack of HuC hardware and we started to use this error
>> > also for all other cases when HuC was not in use or supported.
>> >
>> > Fix that by relying again on HAS_GT_UC macro, since currently
>> > used function intel_huc_is_supported() is based on HuC firmware
>> > support which could be unsupported also due to force disabled
>> > GuC firmware.
>> >
>> > Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> > Cc: Tony Ye <tony.ye at intel.com>
>>
>> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>
> Once upon a time did you (Michal) not argue we should indicate the lack
> of firmware in the error code? Something like
>
> if (!HAS_GT_UC(gt->i915))
> 	return -ENODEV;
>
> if (!intel_huc_is_supported(huc))
> 	return -ENOEXEC;

Yes, we discussed this here [1] together with [2] but we didn't
conclude our discussion due to different opinions on how represent
some states, in particular "manually disabled" state.

In this patch I just wanted to restore old notation.

But we can start new discussion, here is summary:

------------------+----------+----------+----------
  HuC state        | today*   | option A | option B
------------------+----------+----------+----------
no HuC hardware   | -ENODEV  | -ENODEV  | -ENODEV
GuC fw disabled   |   0      |     0    | -EOPNOTSUPP
HuC fw disabled   |   0      |     0    | -EOPNOTSUPP
HuC fw missing    |   0      | -ENOPKG  | -ENOEXEC
HuC fw error      |   0      | -ENOEXEC | -ENOEXEC
HuC fw fail       |   0      | -EACCES  |    0
HuC authenticated |   1      |     1    |    1
------------------+----------+----------+----------

Note that all above should be compatible with media driver,
which explicitly looks for no error and value 1

Michal

[1] https://patchwork.freedesktop.org/patch/306419/?series=61001&rev=1
[2] https://patchwork.freedesktop.org/series/60800/#rev1