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

[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.

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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