[Intel-gfx] [PATCH 47/47] drm/i915/guc: Unblock GuC submission on Gen11+

[John Harrison]

On 7/3/2021 01:21, Martin Peres wrote:
> On 02/07/2021 18:07, Michal Wajdeczko wrote:
>> On 02.07.2021 10:09, Martin Peres wrote:
>>> On 02/07/2021 10:29, Pekka Paalanen wrote:
>>>> On Thu, 1 Jul 2021 21:28:06 +0200
>>>> Daniel Vetter <daniel at ffwll.ch> wrote:
>>>>
>>>>> On Thu, Jul 1, 2021 at 8:27 PM Martin Peres <martin.peres at free.fr>
>>>>> wrote:
>>>>>>
>>>>>> On 01/07/2021 11:14, Pekka Paalanen wrote:
>>>>>>> On Wed, 30 Jun 2021 11:58:25 -0700
>>>>>>> John Harrison <john.c.harrison at intel.com> wrote:
>>>>>>>> On 6/30/2021 01:22, Martin Peres wrote:
>>>>>>>>> On 24/06/2021 10:05, Matthew Brost wrote:
>>>>>>>>>> From: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>>>>>>>>>>
>>>>>>>>>> Unblock GuC submission on Gen11+ platforms.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>>>>>>>>>> Signed-off-by: Daniele Ceraolo Spurio
>>>>>>>>>> <daniele.ceraolospurio at intel.com>
>>>>>>>>>> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
>>>>>>>>>> ---
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_guc.h |  1 +
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c |  8 ++++++++
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_guc_submission.h |  3 +--
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_uc.c | 14
>>>>>>>>>> +++++++++-----
>>>>>>>>>>      4 files changed, 19 insertions(+), 7 deletions(-)
>>>>>>>
>>>>>>> ...
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>>>>>>>>> index 7a69c3c027e9..61be0aa81492 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
>>>>>>>>>> @@ -34,8 +34,15 @@ static void uc_expand_default_options(struct
>>>>>>>>>> intel_uc *uc)
>>>>>>>>>>              return;
>>>>>>>>>>          }
>>>>>>>>>>      -    /* Default: enable HuC authentication only */
>>>>>>>>>> -    i915->params.enable_guc = ENABLE_GUC_LOAD_HUC;
>>>>>>>>>> +    /* Intermediate platforms are HuC authentication only */
>>>>>>>>>> +    if (IS_DG1(i915) || IS_ALDERLAKE_S(i915)) {
>>>>>>>>>> +        drm_dbg(&i915->drm, "Disabling GuC only due to old
>>>>>>>>>> platform\n");
>>>>>>>>>
>>>>>>>>> This comment does not seem accurate, given that DG1 is barely
>>>>>>>>> out, and
>>>>>>>>> ADL is not out yet. How about:
>>>>>>>>>
>>>>>>>>> "Disabling GuC on untested platforms"?
>>>>>>>> Just because something is not in the shops yet does not mean it is
>>>>>>>> new.
>>>>>>>> Technology is always obsolete by the time it goes on sale.
>>>>>>>
>>>>>>> That is a very good reason to not use terminology like "new", 
>>>>>>> "old",
>>>>>>> "current", "modern" etc. at all.
>>>>>>>
>>>>>>> End users like me definitely do not share your interpretation of
>>>>>>> "old".
>>>>>>
>>>>>> Yep, old and new is relative. In the end, what matters is the
>>>>>> validation
>>>>>> effort, which is why I was proposing "untested platforms".
>>>>>>
>>>>>> Also, remember that you are not writing these messages for Intel
>>>>>> engineers, but instead are writing for Linux *users*.
>>>>>
>>>>> It's drm_dbg. Users don't read this stuff, at least not users with no
>>>>> clue what the driver does and stuff like that.
>>>>
>>>> If I had a problem, I would read it, and I have no clue what anything
>>>> of that is.
>>>
>>> Exactly.
I don't see how replacing 'old' for 'untested' helps anybody to 
understand anything. Untested just implies we can't be bothered to test 
stuff before publishing it. And as previously stated, this is purely a 
political decision not a technical one. Sure, change the message to be 
'Disabling GuC submission but enabling HuC loading via GuC on platform 
XXX' if that makes it clearer what is going on. Or just drop the message 
completely. It's simply explaining what the default option is for the 
current platform which you can also get by reading the code. However, I 
disagree that 'untested' is the correct message. Quite a lot of testing 
has been happening on TGL+ with GuC submission enabled.

>>>
>>> This level of defense for what is clearly a bad *debug* message (at the
>>> very least, the grammar) makes no sense at all!
>>>
>>> I don't want to hear arguments like "Not my patch" from a developer
>>> literally sending the patch to the ML and who added his SoB to the
>>> patch, playing with words, or minimizing the problem of having such a
>>> message.
>>
>> Agree that 'not my patch' is never a good excuse, but equally we can't
>> blame original patch author as patch was updated few times since then.
>
> I never wanted to blame the author here, I was only speaking about the 
> handling of feedback on the patch.
>
>>
>> Maybe to avoid confusions and simplify reviews, we could split this
>> patch into two smaller: first one that really unblocks GuC submission on
>> all Gen11+ (see __guc_submission_supported) and second one that updates
>> defaults for Gen12+ (see uc_expand_default_options), as original patch
>> (from ~2019) evolved more than what title/commit message says.
>
> Both work for me, as long as it is a collaborative effort.
I'm not seeing how splitting the patch up fixes the complaints about the 
debug message.

And to be clear, no-one is actually arguing for a code change as such? 
The issue is just about the text of the debug message? Or did I miss 
something somewhere?

John.


>
> Cheers,
> Martin
>
>>
>> Then we can fix all messaging and make sure it's clear and understood.
>>
>> Thanks,
>> Michal
>>
>>>
>>> All of the above are just clear signals for the community to get off
>>> your playground, which is frankly unacceptable. Your email address does
>>> not matter.
>>>
>>> In the spirit of collaboration, your response should have been "Good
>>> catch, how about XXXX or YYYY?". This would not have wasted everyone's
>>> time in an attempt to just have it your way.
>>>
>>> My level of confidence in this GuC transition was already low, but you
>>> guys are working hard to shoot yourself in the foot. Trust should be
>>> earned!
>>>
>>> Martin
>>>
>>>>
>>>>
>>>> Thanks,
>>>> pq
>>>>
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