Re: [PATCH v6 1/2] drm/xe/guc: Eliminate RPe caching for SLPC parameter handling

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

On Wed, Nov 05, 2025 at 01:27:37AM +0530, Sk Anirban wrote:
> RPe is runtime-determined by PCODE and caching it caused stale values,
> leading to incorrect GuC SLPC parameter settings.
> Drop the cached rpe_freq field and query fresh values from hardware
> on each use to ensure GuC SLPC parameters reflect current RPe.
> 
> v2: Remove cached RPe frequency field (Rodrigo)
> v3: Remove extra variable (Vinay)
>     Modify function name (Vinay)
> v4: Maintain a separate function for PVC (Rodrigo)
> v5: Avoid RPn update while fetching RPe frequency (Rodrigo)

dang, now I regret on having asked that... I'm not trusting on the
CI results any longer.

Did you run this full xe_gt_freq tests in your machine?
I forgot the machine that made us to introduce this rpn hack...

> 
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5166
> Signed-off-by: Sk Anirban <sk.anirban@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_pc.c       | 68 ++++++++++++++--------------
>  drivers/gpu/drm/xe/xe_guc_pc_types.h |  2 -
>  2 files changed, 35 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> index ff22235857f8..efa9318c4587 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> @@ -331,7 +331,7 @@ static int pc_set_min_freq(struct xe_guc_pc *pc, u32 freq)
>  	 * Our goal is to have the admin choices respected.
>  	 */
>  	pc_action_set_param(pc, SLPC_PARAM_IGNORE_EFFICIENT_FREQUENCY,
> -			    freq < pc->rpe_freq);
> +			    freq < xe_guc_pc_get_rpe_freq(pc));
>  
>  	return pc_action_set_param(pc,
>  				   SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
> @@ -376,7 +376,7 @@ static void mtl_update_rpa_value(struct xe_guc_pc *pc)
>  	pc->rpa_freq = decode_freq(REG_FIELD_GET(MTL_RPA_MASK, reg));
>  }
>  
> -static void mtl_update_rpe_value(struct xe_guc_pc *pc)
> +static u32 mtl_get_rpe_freq(struct xe_guc_pc *pc)
>  {
>  	struct xe_gt *gt = pc_to_gt(pc);
>  	u32 reg;
> @@ -386,7 +386,7 @@ static void mtl_update_rpe_value(struct xe_guc_pc *pc)
>  	else
>  		reg = xe_mmio_read32(&gt->mmio, MTL_GT_RPE_FREQUENCY);
>  
> -	pc->rpe_freq = decode_freq(REG_FIELD_GET(MTL_RPE_MASK, reg));
> +	return decode_freq(REG_FIELD_GET(MTL_RPE_MASK, reg));
>  }
>  
>  static void tgl_update_rpa_value(struct xe_guc_pc *pc)
> @@ -409,24 +409,22 @@ static void tgl_update_rpa_value(struct xe_guc_pc *pc)
>  	}
>  }
>  
> -static void tgl_update_rpe_value(struct xe_guc_pc *pc)
> +static u32 pvc_get_rpe_freq(struct xe_guc_pc *pc)
>  {
>  	struct xe_gt *gt = pc_to_gt(pc);
> -	struct xe_device *xe = gt_to_xe(gt);
>  	u32 reg;
>  
> -	/*
> -	 * For PVC we still need to use fused RP1 as the approximation for RPe
> -	 * For other platforms than PVC we get the resolved RPe directly from
> -	 * PCODE at a different register
> -	 */
> -	if (xe->info.platform == XE_PVC) {
> -		reg = xe_mmio_read32(&gt->mmio, PVC_RP_STATE_CAP);
> -		pc->rpe_freq = REG_FIELD_GET(RP1_MASK, reg) * GT_FREQUENCY_MULTIPLIER;
> -	} else {
> -		reg = xe_mmio_read32(&gt->mmio, FREQ_INFO_REC);
> -		pc->rpe_freq = REG_FIELD_GET(RPE_MASK, reg) * GT_FREQUENCY_MULTIPLIER;
> -	}
> +	reg = xe_mmio_read32(&gt->mmio, PVC_RP_STATE_CAP);
> +	return REG_FIELD_GET(RP1_MASK, reg) * GT_FREQUENCY_MULTIPLIER;
> +}
> +
> +static u32 tgl_get_rpe_freq(struct xe_guc_pc *pc)
> +{
> +	struct xe_gt *gt = pc_to_gt(pc);
> +	u32 reg;
> +
> +	reg = xe_mmio_read32(&gt->mmio, FREQ_INFO_REC);
> +	return REG_FIELD_GET(RPE_MASK, reg) * GT_FREQUENCY_MULTIPLIER;
>  }
>  
>  static void pc_update_rp_values(struct xe_guc_pc *pc)
> @@ -434,20 +432,10 @@ static void pc_update_rp_values(struct xe_guc_pc *pc)
>  	struct xe_gt *gt = pc_to_gt(pc);
>  	struct xe_device *xe = gt_to_xe(gt);
>  
> -	if (GRAPHICS_VERx100(xe) >= 1270) {
> +	if (GRAPHICS_VERx100(xe) >= 1270)
>  		mtl_update_rpa_value(pc);
> -		mtl_update_rpe_value(pc);
> -	} else {
> +	else
>  		tgl_update_rpa_value(pc);
> -		tgl_update_rpe_value(pc);
> -	}
> -
> -	/*
> -	 * RPe is decided at runtime by PCODE. In the rare case where that's
> -	 * smaller than the fused min, we will trust the PCODE and use that
> -	 * as our minimum one.
> -	 */
> -	pc->rpn_freq = min(pc->rpn_freq, pc->rpe_freq);
>  }
>  
>  /**
> @@ -561,9 +549,23 @@ u32 xe_guc_pc_get_rpa_freq(struct xe_guc_pc *pc)
>   */
>  u32 xe_guc_pc_get_rpe_freq(struct xe_guc_pc *pc)
>  {
> -	pc_update_rp_values(pc);
> +	struct xe_gt *gt = pc_to_gt(pc);
> +	struct xe_device *xe = gt_to_xe(gt);
> +	u32 freq;
>  
> -	return pc->rpe_freq;
> +	/*
> +	 * For PVC we still need to use fused RP1 as the approximation for RPe
> +	 * For other platforms than PVC we get the resolved RPe directly from
> +	 * PCODE at a different register
> +	 */
> +	if (GRAPHICS_VERx100(xe) == 1260)
> +		freq = pvc_get_rpe_freq(pc);
> +	else if (GRAPHICS_VERx100(xe) >= 1270)
> +		freq = mtl_get_rpe_freq(pc);
> +	else
> +		freq = tgl_get_rpe_freq(pc);
> +
> +	return freq;
>  }
>  
>  /**
> @@ -1022,7 +1024,7 @@ static int pc_set_mert_freq_cap(struct xe_guc_pc *pc)
>  	/*
>  	 * Ensure min and max are bound by MERT_FREQ_CAP until driver loads.
>  	 */
> -	ret = pc_set_min_freq(pc, min(pc->rpe_freq, pc_max_freq_cap(pc)));
> +	ret = pc_set_min_freq(pc, min(xe_guc_pc_get_rpe_freq(pc), pc_max_freq_cap(pc)));
>  	if (!ret)
>  		ret = pc_set_max_freq(pc, min(pc->rp0_freq, pc_max_freq_cap(pc)));
>  
> @@ -1340,7 +1342,7 @@ static void xe_guc_pc_fini_hw(void *arg)
>  	XE_WARN_ON(xe_guc_pc_stop(pc));
>  
>  	/* Bind requested freq to mert_freq_cap before unload */
> -	pc_set_cur_freq(pc, min(pc_max_freq_cap(pc), pc->rpe_freq));
> +	pc_set_cur_freq(pc, min(pc_max_freq_cap(pc), xe_guc_pc_get_rpe_freq(pc)));
>  
>  	xe_force_wake_put(gt_to_fw(pc_to_gt(pc)), fw_ref);
>  }
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc_types.h b/drivers/gpu/drm/xe/xe_guc_pc_types.h
> index 5e4ea53fbee6..f27c05d81706 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc_types.h
> +++ b/drivers/gpu/drm/xe/xe_guc_pc_types.h
> @@ -21,8 +21,6 @@ struct xe_guc_pc {
>  	u32 rp0_freq;
>  	/** @rpa_freq: HW RPa frequency - The Achievable one */
>  	u32 rpa_freq;
> -	/** @rpe_freq: HW RPe frequency - The Efficient one */
> -	u32 rpe_freq;
>  	/** @rpn_freq: HW RPN frequency - The Minimum one */
>  	u32 rpn_freq;
>  	/** @user_requested_min: Stash the minimum requested freq by user */
> -- 
> 2.43.0
>