Re: [PATCH 2/2] drm/xe: Add wa_14025941587 to xe2, xe3 and xe3p platforms

["Belgaumkar, Vinay" <vinay.belgaumkar@intel.com>]

On 9/9/2026 9:18 AM, tilak.tirumalesh.tangudu@intel.com wrote:
> From: Tangudu Tilak Tirumalesh <tilak.tirumalesh.tangudu@intel.com>
>
> Avoid programming the IDLEDLY timer to less than 5 microseconds.
> Apply wa_14025941587 to Graphics Versions 20.01 to 35.11
> and Media Versions 13.01 to 35.03
>
> v2: Use xe_rtp_match_not_sriov_vf, move to local variable
>      Remove warn and other knits            - Matt R
>
> v3: Add verbose comment - Tejas
>
> v4: Restore IDLE_DLY register on engine reset.
>      Add it to GUC save-restore list. -Vivek
>
> v5: Extend WA to Media Versions 13.01 to 35.03 - Vinay
>
> v6: Avoid clearing inhibit switch - Bala
>      Refactor code accordingly by adding idle_reg_val.
>
> v7: Rebased with the divide-by-zero/overflow guards living in
>      a separate hardening patch.
>
> v8: Preserve the Wa_16023105232 floor (DIV_ROUND_DOWN_ULL) and the
>      maxcnt == 0 guard from the hardening patch. Round up
>      (DIV_ROUND_UP_ULL) the Wa_14025941587 minimum conversion instead,
>      so the tick-quantized delay cannot round back below 5 us.
>
> Assisted-by: GitHub_Copilot:claude-opus-4.8
> Signed-off-by: Tangudu Tilak Tirumalesh <tilak.tirumalesh.tangudu@intel.com>

LGTM,

Reviewed-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>

> ---
>   drivers/gpu/drm/xe/xe_guc_ads.c    |  2 +-
>   drivers/gpu/drm/xe/xe_hw_engine.c  | 69 ++++++++++++++++++++++++------
>   drivers/gpu/drm/xe/xe_wa_oob.rules |  2 +
>   3 files changed, 60 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_guc_ads.c b/drivers/gpu/drm/xe/xe_guc_ads.c
> index ff8eee3831aa..58a3f6293ce4 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ads.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ads.c
> @@ -864,7 +864,7 @@ static unsigned int guc_mmio_regset_write(struct xe_guc_ads *ads,
>   		}
>   	}
>   
> -	if (XE_GT_WA(hwe->gt, 16023105232))
> +	if (XE_GT_WA(hwe->gt, 16023105232) || XE_GT_WA(hwe->gt, 14025941587))
>   		guc_mmio_regset_write_one(ads, regset_map,
>   					  RING_IDLEDLY(hwe->mmio_base),
>   					  count++);
> diff --git a/drivers/gpu/drm/xe/xe_hw_engine.c b/drivers/gpu/drm/xe/xe_hw_engine.c
> index c86890e09b55..37cd7fe38c2b 100644
> --- a/drivers/gpu/drm/xe/xe_hw_engine.c
> +++ b/drivers/gpu/drm/xe/xe_hw_engine.c
> @@ -588,33 +588,78 @@ static void hw_engine_init_early(struct xe_gt *gt, struct xe_hw_engine *hwe,
>   static void adjust_idledly(struct xe_hw_engine *hwe)
>   {
>   	struct xe_gt *gt = hwe->gt;
> -	u32 idledly, maxcnt;
> +	u32 idledly, idledly_reg_val, maxcnt;
>   	u32 idledly_units_ps = 8 * gt->info.timestamp_base;
>   	u32 maxcnt_units_ns = 640;
> -	bool inhibit_switch = 0;
> +	bool inhibit_switch = false;
> +	bool wa_applied = false;
> +	bool clamped_below_maxcnt = false;
> +
> +	if ((!IS_SRIOV_VF(gt_to_xe(hwe->gt)) && XE_GT_WA(gt, 16023105232)) ||
> +	    XE_GT_WA(gt, 14025941587)) {
> +		u32 mincnt_idledly_ns = 5000;
>   
> -	if (!IS_SRIOV_VF(gt_to_xe(hwe->gt)) && XE_GT_WA(gt, 16023105232)) {
>   		/* xe_gt_clock_init() zeroes timestamp_base on unknown crystal clock. */
>   		if (!idledly_units_ps) {
>   			xe_gt_warn(gt, "idledly WA skipped: timestamp_base is 0\n");
>   			return;
>   		}
>   
> -		idledly = xe_mmio_read32(&gt->mmio, RING_IDLEDLY(hwe->mmio_base));
> +		idledly_reg_val = xe_mmio_read32(&gt->mmio, RING_IDLEDLY(hwe->mmio_base));
>   		maxcnt = xe_mmio_read32(&gt->mmio, RING_PWRCTX_MAXCNT(hwe->mmio_base));
>   
> -		inhibit_switch = idledly & INHIBIT_SWITCH_UNTIL_PREEMPTED;
> -		idledly = REG_FIELD_GET(IDLE_DELAY, idledly);
> +		inhibit_switch = idledly_reg_val & INHIBIT_SWITCH_UNTIL_PREEMPTED;
> +		idledly = REG_FIELD_GET(IDLE_DELAY, idledly_reg_val);
>   		idledly = DIV_ROUND_CLOSEST_ULL((u64)idledly * idledly_units_ps, 1000);
>   		maxcnt = REG_FIELD_GET(IDLE_WAIT_TIME, maxcnt);
>   		maxcnt *= maxcnt_units_ns;
>   
> -		if (xe_gt_WARN_ON(gt, idledly >= maxcnt || inhibit_switch)) {
> -			/* Floor below maxcnt; write 0 to still clear the inhibit bit. */
> -			idledly = maxcnt ?
> -				DIV_ROUND_DOWN_ULL((u64)(maxcnt - 1) * 1000,
> -						   idledly_units_ps) : 0;
> -			xe_mmio_write32(&gt->mmio, RING_IDLEDLY(hwe->mmio_base), idledly);
> +		/*
> +		 * Wa_14025941587 is applied before Wa_16023105232, which has
> +		 * higher priority; the two are not expected to conflict.
> +		 */
> +		if (XE_GT_WA(gt, 14025941587) &&
> +		    idledly < mincnt_idledly_ns) {
> +			idledly = mincnt_idledly_ns;
> +			wa_applied = true;
> +		}
> +
> +		if (XE_GT_WA(gt, 16023105232) &&
> +		    xe_gt_WARN_ON(gt, idledly >= maxcnt || inhibit_switch)) {
> +			/* maxcnt may be 0 if IDLE_WAIT_TIME is unprogrammed. */
> +			idledly = maxcnt ? maxcnt - 1 : 0;
> +			clamped_below_maxcnt = true;
> +			wa_applied = true;
> +			/* inhibit_switch override to keep
> +			 * semantics of Wa_16023105232
> +			 */
> +			if (inhibit_switch)
> +				idledly_reg_val &= ~INHIBIT_SWITCH_UNTIL_PREEMPTED;
> +		}
> +
> +		if (wa_applied) {
> +			u32 idledly_ticks;
> +
> +			/*
> +			 * Wa_16023105232 requires idledly < maxcnt, so floor
> +			 * that clamp; otherwise round up to guarantee the
> +			 * Wa_14025941587 minimum survives tick quantization.
> +			 */
> +			if (clamped_below_maxcnt)
> +				idledly_ticks = DIV_ROUND_DOWN_ULL((u64)idledly * 1000,
> +								   idledly_units_ps);
> +			else
> +				idledly_ticks = DIV_ROUND_UP_ULL((u64)idledly * 1000,
> +								 idledly_units_ps);
> +
> +			idledly_reg_val &= ~IDLE_DELAY;
> +			idledly_reg_val |= REG_FIELD_PREP(IDLE_DELAY, idledly_ticks);
> +			xe_gt_dbg(gt, "idledly %s: set %u max=%u inh=%u ts=%u\n",
> +				  hwe->name, idledly, maxcnt,
> +				  !!inhibit_switch, gt->info.timestamp_base);
> +			xe_mmio_write32(&gt->mmio,
> +					RING_IDLEDLY(hwe->mmio_base),
> +					idledly_reg_val);
>   		}
>   	}
>   }
> diff --git a/drivers/gpu/drm/xe/xe_wa_oob.rules b/drivers/gpu/drm/xe/xe_wa_oob.rules
> index dd69ad07f7a9..3001155f8d09 100644
> --- a/drivers/gpu/drm/xe/xe_wa_oob.rules
> +++ b/drivers/gpu/drm/xe/xe_wa_oob.rules
> @@ -72,3 +72,5 @@
>   16029897822	MEDIA_VERSION(3500)
>   		GRAPHICS_VERSION(3510)
>   14027054324	GRAPHICS_VERSION(3511)
> +14025941587	GRAPHICS_VERSION_RANGE(2001, 3511), FUNC(xe_rtp_match_not_sriov_vf)
> +		MEDIA_VERSION_RANGE(1301, 3503), FUNC(xe_rtp_match_not_sriov_vf)