Re: [PATCH v4] drm/xe/ptl: Disable DCC on PTL

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Jan 23, 2026 at 04:59:17PM -0800, Vinay Belgaumkar wrote:
> On PTL, the recommendation is to disable DCC(Duty Cycle Control) as
> it may cause some regressions due to added latencies. Upcoming GuC
> releases will disable DCC on PTL as well, but we need to force it in
> KMD so that this behavior is propagated to older kernels.
> 
> v2: Update commit message (Rodrigo)
> v3: Rebase
> v4: Fix BAT issue

Since the only real change in v4 was the typo, I have modified this
note while pushing the patch.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
and pushed

Thanks,
Rodrigo.

> 
> Fixes: 5cdb71d3b0db ("drm/xe/ptl: Add GuC FW definition for PTL")
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Vinay Belgaumkar<vinay.belgaumkar@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_pc.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> index 54702a0fd05b..5e5495a39a3c 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> @@ -1198,6 +1198,36 @@ int xe_guc_pc_set_power_profile(struct xe_guc_pc *pc, const char *buf)
>  	return ret;
>  }
>  
> +static int pc_action_set_dcc(struct xe_guc_pc *pc, bool enable)
> +{
> +	int ret;
> +
> +	ret = pc_action_set_param(pc,
> +				  SLPC_PARAM_TASK_ENABLE_DCC,
> +				  enable);
> +	if (!ret)
> +		return pc_action_set_param(pc,
> +					   SLPC_PARAM_TASK_DISABLE_DCC,
> +					   !enable);
> +	else
> +		return ret;
> +}
> +
> +static int pc_modify_defaults(struct xe_guc_pc *pc)
> +{
> +	struct xe_device *xe = pc_to_xe(pc);
> +	struct xe_gt *gt = pc_to_gt(pc);
> +	int ret = 0;
> +
> +	if (xe->info.platform == XE_PANTHERLAKE) {
> +		ret = pc_action_set_dcc(pc, false);
> +		if (unlikely(ret))
> +			xe_gt_err(gt, "Failed to modify DCC default: %pe\n", ERR_PTR(ret));
> +	}
> +
> +	return ret;
> +}
> +
>  /**
>   * xe_guc_pc_start - Start GuC's Power Conservation component
>   * @pc: Xe_GuC_PC instance
> @@ -1249,6 +1279,10 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
>  			   ktime_ms_delta(ktime_get(), earlier));
>  	}
>  
> +	ret = pc_modify_defaults(pc);
> +	if (ret)
> +		return ret;
> +
>  	ret = pc_init_freqs(pc);
>  	if (ret)
>  		return ret;
> -- 
> 2.38.1
>