[Nouveau] [RFC PATCH 13/13] clk: thermal throttling

[Pierre Moreau]

On 2017-07-21 — 23:55, Karol Herbst wrote:
> Signed-off-by: Karol Herbst <karolherbst at gmail.com>
> ---
>  drm/nouveau/include/nvkm/subdev/clk.h |  1 +
>  drm/nouveau/nvkm/subdev/clk/base.c    | 35 +++++++++++++++++++++++++++++++----
>  2 files changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/drm/nouveau/include/nvkm/subdev/clk.h b/drm/nouveau/include/nvkm/subdev/clk.h
> index f5ff1fd9..b79bf657 100644
> --- a/drm/nouveau/include/nvkm/subdev/clk.h
> +++ b/drm/nouveau/include/nvkm/subdev/clk.h
> @@ -106,6 +106,7 @@ struct nvkm_clk {
>  	u8  temp;
>  	u8  max_temp;
>  	u8  relax_temp;
> +	bool throttled;
>  
>  	bool allow_reclock;
>  #define NVKM_CLK_BOOST_NONE 0x0
> diff --git a/drm/nouveau/nvkm/subdev/clk/base.c b/drm/nouveau/nvkm/subdev/clk/base.c
> index 60edb57b..34642000 100644
> --- a/drm/nouveau/nvkm/subdev/clk/base.c
> +++ b/drm/nouveau/nvkm/subdev/clk/base.c
> @@ -279,7 +279,7 @@ nvkm_pstate_prog(struct nvkm_clk *clk, int pstateid)
>  	struct nvkm_fb *fb = subdev->device->fb;
>  	struct nvkm_pci *pci = subdev->device->pci;
>  	struct nvkm_pstate *pstate;
> -	int ret;
> +	int ret, cstate;
>  
>  	if (pstateid == NVKM_CLK_PSTATE_DEFAULT)
>  		return 0;
> @@ -308,7 +308,12 @@ nvkm_pstate_prog(struct nvkm_clk *clk, int pstateid)
>  		ram->func->tidy(ram);
>  	}
>  
> -	return nvkm_cstate_prog(clk, pstate, clk->exp_cstateid);
> +	if (clk->throttled)
> +		cstate = list_first_entry(&pstate->list, struct nvkm_cstate, head)->id;
> +	else
> +		cstate = clk->exp_cstateid;
> +
> +	return nvkm_cstate_prog(clk, pstate, cstate);
>  }
>  
>  static void
> @@ -333,12 +338,17 @@ nvkm_clk_update_work(struct work_struct *work)
>  
>  	pstate = clk->pwrsrc ? clk->ustate_ac : clk->ustate_dc;
>  	if (clk->state_nr && pstate != -1) {
> -		pstate = (pstate < 0) ? clk->astate : pstate;
> +		if (clk->throttled)
> +			pstate = list_first_entry(&clk->states, struct nvkm_pstate, head)->pstate;
> +		else
> +			pstate = (pstate < 0) ? clk->astate : pstate;
>  	} else {
>  		pstate = NVKM_CLK_PSTATE_DEFAULT;
>  	}
>  
> -	nvkm_trace(subdev, "-> %d\n", pstate);
> +	nvkm_trace(subdev, "P %d PWR %d U(AC) %d U(DC) %d A %d C %d T %d°C\n",
> +		   pstate, clk->pwrsrc, clk->ustate_ac, clk->ustate_dc,
> +		   clk->astate, clk->exp_cstateid, clk->temp);
>  
>  	/* only call into the code if the GPU is powered on */
>  	if ((!clk->pstate || pstate != clk->pstate->pstate)
> @@ -574,9 +584,25 @@ nvkm_clk_astate(struct nvkm_clk *clk, int req, int rel, bool wait)
>  int
>  nvkm_clk_tstate(struct nvkm_clk *clk, u8 temp)
>  {
> +	struct nvkm_subdev *subdev = &clk->subdev;
>  	if (clk->temp == temp)
>  		return 0;
>  	clk->temp = temp;
> +	if (clk->max_temp && clk->relax_temp) {
> +		if (!clk->throttled && temp > clk->max_temp) {
> +			nvkm_warn(subdev,
> +				  "temperature (%d C) hit the 'downclock' "
> +				  "threshold\n",
> +				  temp);
> +			clk->throttled = true;
> +		} else if (clk->throttled && temp < clk->relax_temp) {
> +			nvkm_warn(subdev,
> +				  "temperature (%d C) went below the "
> +				  "'relax' threshold\n",
> +				  temp);
> +			clk->throttled = false;

I don't think this should be a warning. Maybe an `nvkm_info()` instead?

Also, should the throttled status be reset/recomputed after suspend/resume cycle?

> +		}
> +	}
>  	return nvkm_clk_update(clk, false);
>  }
>  
> @@ -737,6 +763,7 @@ nvkm_clk_ctor(const struct nvkm_clk_func *func, struct nvkm_device *device,
>  	clk->ustate_dc = -1;
>  	clk->exp_cstateid = NVKM_CLK_CSTATE_DEFAULT;
>  	clk->temp = 90; /* reasonable default value */
> +	clk->throttled = false;
>  
>  	clk->allow_reclock = allow_reclock;
>  
> -- 
> 2.13.2
> 
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