[PATCH] drm/amdgpu: Driver needn't request RLC safe mode for gfx MGCG

[Lazar, Lijo]

On 12/18/2024 1:01 PM, Prike Liang wrote:
> In accordance with the MGCG HW sequence, there is no need for
> the driver to request safe mode before enabling GFX MGCG. For
> GFX10 and later versions, maintaining safe mode is acceptable
> for GFX MGCG; otherwise, there will be an increased overhead
> during safe mode entry and exit when enabling other GFX clock
> gating. So now this change only apply gfx9 and gfx8, and without
> polling safe mode, the time required for GFX MGCG entry and exit
> will be reduced on GFX9 and GFX8 systems.
> 

The only place these get called is *update_gfx_clock_gating(). So it's
better to keep a single safe mode/entry exit for that rather than
keeping it separately for each function call within that.

For gfx_v8.0, somehow reference sequences use RLC safe mode entry/exit
for MGCG.

Thanks,
Lijo

> Signed-off-by: Prike Liang <Prike.Liang at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c | 4 ----
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 4 ----
>  2 files changed, 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> index af73f85527b7..690235dafec1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> @@ -5639,8 +5639,6 @@ static void gfx_v8_0_update_medium_grain_clock_gating(struct amdgpu_device *adev
>  {
>  	uint32_t temp, data;
>  
> -	amdgpu_gfx_rlc_enter_safe_mode(adev, 0);
> -
>  	/* It is disabled by HW by default */
>  	if (enable && (adev->cg_flags & AMD_CG_SUPPORT_GFX_MGCG)) {
>  		if (adev->cg_flags & AMD_CG_SUPPORT_GFX_MGLS) {
> @@ -5734,8 +5732,6 @@ static void gfx_v8_0_update_medium_grain_clock_gating(struct amdgpu_device *adev
>  		/* 7- wait for RLC_SERDES_CU_MASTER & RLC_SERDES_NONCU_MASTER idle */
>  		gfx_v8_0_wait_for_rlc_serdes(adev);
>  	}
> -
> -	amdgpu_gfx_rlc_exit_safe_mode(adev, 0);
>  }
>  
>  static void gfx_v8_0_update_coarse_grain_clock_gating(struct amdgpu_device *adev,
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 4b5006dc3d34..6dec5383ba17 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -4964,8 +4964,6 @@ static void gfx_v9_0_update_medium_grain_clock_gating(struct amdgpu_device *adev
>  {
>  	uint32_t data, def;
>  
> -	amdgpu_gfx_rlc_enter_safe_mode(adev, 0);
> -
>  	/* It is disabled by HW by default */
>  	if (enable && (adev->cg_flags & AMD_CG_SUPPORT_GFX_MGCG)) {
>  		/* 1 - RLC_CGTT_MGCG_OVERRIDE */
> @@ -5030,8 +5028,6 @@ static void gfx_v9_0_update_medium_grain_clock_gating(struct amdgpu_device *adev
>  			WREG32_SOC15(GC, 0, mmCP_MEM_SLP_CNTL, data);
>  		}
>  	}
> -
> -	amdgpu_gfx_rlc_exit_safe_mode(adev, 0);
>  }
>  
>  static void gfx_v9_0_update_3d_clock_gating(struct amdgpu_device *adev,