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

[Christian König]

Am 11.09.2018 um 17:06 schrieb James Zhu:
>
>
>
> On 2018-09-11 10:44 AM, Alex Deucher wrote:
>> On Mon, Sep 10, 2018 at 4:34 PM James Zhu<jzhums at gmail.com>  wrote:
>>> Signed-off-by: James Zhu<James.Zhu at amd.com>
>>>
>>> When VCN PG state is unchanged, it is unnecessary to reset
>>> power gate state again.
>> Don't you need to initialize and store the PG state somewhere?  You
>> are just using a local variable here.
>>
>> Alex
>>
> Hi Alex,
>
> I used */static/* for this local state variable(*cur_state*) with 
> initialization state AMD_PG_STATE_GATE.

That won't work correctly. A "static" variable is global, but the power 
state is per device.

Regards,
Christian.

> this variable's scope is only inside this function, but it's 
> initialization is done
> once at compile time and it's lifetime will last until the driver exit.
>
> Since it is only used inside this function, I didn't put it into 
> struct amdgpu_vcn.
>
> Best Regards!
> James Zhu
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c | 13 +++++++++++--
>>>   1 file changed, 11 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>> index 2664bb2..86d98d2 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
>>> @@ -1633,12 +1633,21 @@ 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;
>>> +       static enum amd_powergating_state cur_state = AMD_PG_STATE_GATE;
>>>          struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>>>
>>> +       if (state == 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)
>>> +               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
>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>
>
>
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