[PATCH v2] drm/amdgpu:No action when VCN PG state is unchanged

[Christian König]

Am 21.09.2018 um 14:28 schrieb James Zhu:
>
>
> On 2018-09-20 01:54 PM, Christian König wrote:
>> Am 20.09.2018 um 18:24 schrieb James Zhu:
>>>
>>>
>>> On 2018-09-20 11:49 AM, Alex Deucher wrote:
>>>> On Thu, Sep 20, 2018 at 11:27 AM James Zhu <jamesz at amd.com> wrote:
>>>>>
>>>>>
>>>>> On 2018-09-20 11:14 AM, Alex Deucher wrote:
>>>>>> On Thu, Sep 13, 2018 at 4:56 PM James Zhu <jzhums at gmail.com> wrote:
>>>>>>> When VCN PG state is unchanged, it is unnecessary to reset power
>>>>>>> gate state
>>>>>>>
>>>>>>> Signed-off-by: James Zhu <James.Zhu at amd.com>
>>>>>>> ---
>>>>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h |  1 +
>>>>>>>    drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c   | 12 ++++++++++--
>>>>>>>    2 files changed, 11 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h 
>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
>>>>>>> index 0b0b863..d2219ab 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
>>>>>>> @@ -69,6 +69,7 @@ struct amdgpu_vcn {
>>>>>>>           struct amdgpu_ring      ring_jpeg;
>>>>>>>           struct amdgpu_irq_src   irq;
>>>>>>>           unsigned                num_enc_rings;
>>>>>>> +       enum amd_powergating_state cur_state;
>>>>>> Does the default value (0) at init time properly reflect the default
>>>>>> powergating state?  If so,
>>>>>> Acked-by: Alex Deucher <alexander.deucher at amd.com>
>>>>> Yes, the below code shows it will be set to 0 during driver load 
>>>>> stage.
>>>> Yes, I understand that.  Is 0 (AMD_PG_STATE_GATE) what we want as the
>>>> default though?  The first time the code runs are we going to do the
>>>> right thing or is the code going to return early?  IIRC, the hw
>>>> default is ungated.
>>> cur_state is used for tracking driver SW PG state, not HW  PG state.
>>> I though no matter what HW  PG state is after device powers up, when 
>>> first vcn ring is scheduled to run,
>>> begin_use->set_powergating_state->vcn_v1_0_start->ungate 
>>> power/clock->Boot_VCPU  will be tried.
>>>
>>> For DPG mode, the ungate power/clock , boot VCPU will not actually 
>>> be activated during start setup stage, and
>>> only be activated during ring run stage.
>>
>> Mhm, I wonder if it wouldn't be better to have that functionality one 
>> layer up.
>>
>> E.g. in amdgpu_device_ip_set_powergating_state so that it applies to 
>> all IP blocks in the same way.
> If necessary, I can add support for IP blocks later.

Yeah, agree. In general I'm not doing much with power management, so 
can't judge if that is a good idea or not.

Anyway feel free to add my Acked-by to the patch.

Regards,
Christian.

> James
>>
>> But on the other hand the correct solution looks good to me as well, 
>> so feel free to add my Acked-by as well.
>>
>> Christian.
>>
>>>
>>> James
>>>> Alex
>>>>> int amdgpu_driver_load_kms(struct drm_device *dev, unsigned long 
>>>>> flags)
>>>>> ....
>>>>>       adev = kzalloc(sizeof(struct amdgpu_device), GFP_KERNEL);
>>>>>
>>>>> struct amdgpu_device {
>>>>> ....
>>>>>       struct amdgpu_vcn        vcn;
>>>>>
>>>>> Best Regards!
>>>>> James zhu
>>>>>>>    };
>>>>>>>
>>>>>>>    int amdgpu_vcn_sw_init(struct amdgpu_device *adev);
>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c 
>>>>>>> b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>>>>>> index 2664bb2..2cde0b4 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>>>>>> @@ -1633,12 +1633,20 @@ static int 
>>>>>>> vcn_v1_0_set_powergating_state(void *handle,
>>>>>>>            * revisit this when there is a cleaner line between
>>>>>>>            * the smc and the hw blocks
>>>>>>>            */
>>>>>>> +       int ret;
>>>>>>>           struct amdgpu_device *adev = (struct amdgpu_device 
>>>>>>> *)handle;
>>>>>>>
>>>>>>> +       if(state == adev->vcn.cur_state)
>>>>>>> +               return 0;
>>>>>>> +
>>>>>>>           if (state == AMD_PG_STATE_GATE)
>>>>>>> -               return vcn_v1_0_stop(adev);
>>>>>>> +               ret = vcn_v1_0_stop(adev);
>>>>>>>           else
>>>>>>> -               return vcn_v1_0_start(adev);
>>>>>>> +               ret = vcn_v1_0_start(adev);
>>>>>>> +
>>>>>>> +       if(!ret)
>>>>>>> +               adev->vcn.cur_state = state;
>>>>>>> +       return ret;
>>>>>>>    }
>>>>>>>
>>>>>>>    static const struct amd_ip_funcs vcn_v1_0_ip_funcs = {
>>>>>>> -- 
>>>>>>> 2.7.4
>>>>>>>
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>>>>>>> amd-gfx at lists.freedesktop.org
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>>>
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>>
>