[PATCH v2] drm/xe/lnl: Apply GuC Wa_13011645652

[John Harrison]

On 4/16/2024 12:41, Vinay Belgaumkar wrote:
> Enable WA for a bug that could cause the C6 state machine to hang
> during RC6 exit.
>
> v2: Add comment clarifying the WA (John H)
>
> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> ---
>   drivers/gpu/drm/xe/abi/guc_klvs_abi.h |  1 +
>   drivers/gpu/drm/xe/xe_guc_ads.c       | 34 +++++++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_wa_oob.rules    |  1 +
>   3 files changed, 36 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/abi/guc_klvs_abi.h b/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> index 0972113f6b81..511cf974d585 100644
> --- a/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> +++ b/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> @@ -326,6 +326,7 @@ enum xe_guc_klv_ids {
>   	GUC_WORKAROUND_KLV_BLOCK_INTERRUPTS_WHEN_MGSR_BLOCKED				= 0x9002,
>   	GUC_WORKAROUND_KLV_ID_GAM_PFQ_SHADOW_TAIL_POLLING				= 0x9005,
>   	GUC_WORKAROUND_KLV_ID_DISABLE_MTP_DURING_ASYNC_COMPUTE				= 0x9007,
> +	GUC_WA_KLV_NP_RD_WRITE_TO_CLEAR_RCSM_AT_CGP_LATE_RESTORE			= 0x9008,
>   };
>   
>   #endif
> diff --git a/drivers/gpu/drm/xe/xe_guc_ads.c b/drivers/gpu/drm/xe/xe_guc_ads.c
> index 678ece366056..4e6fc69a4710 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ads.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ads.c
> @@ -282,6 +282,33 @@ static size_t calculate_golden_lrc_size(struct xe_guc_ads *ads)
>   	return total_size;
>   }
>   
> +static void guc_waklv_enable_one_word(struct xe_guc_ads *ads,
> +				      enum xe_guc_klv_ids klv_id,
> +				      u32 value,
> +				      u32 *offset, u32 *remain)
> +{
> +	u32 size;
> +	u32 klv_entry[] = {
> +		/* 16:16 key/length */
> +		FIELD_PREP(GUC_KLV_0_KEY, klv_id) |
> +		FIELD_PREP(GUC_KLV_0_LEN, 1),
> +		value,
> +		/* 1 dword data */
> +	};
> +
> +	size = sizeof(klv_entry);
> +
> +	if (*remain < size) {
> +		drm_warn(&ads_to_xe(ads)->drm,
> +			 "w/a klv buffer too small to add klv id %d\n", klv_id);
> +	} else {
> +		xe_map_memcpy_to(ads_to_xe(ads), ads_to_map(ads), *offset,
> +				 klv_entry, size);
> +		*offset += size;
> +		*remain -= size;
> +	}
> +}
> +
>   static void guc_waklv_enable_simple(struct xe_guc_ads *ads,
>   				    enum xe_guc_klv_ids klv_id, u32 *offset, u32 *remain)
>   {
> @@ -327,6 +354,13 @@ static void guc_waklv_init(struct xe_guc_ads *ads)
>   					GUC_WORKAROUND_KLV_ID_DISABLE_MTP_DURING_ASYNC_COMPUTE,
>   					&offset, &remain);
>   
> +	/* GuC will restore register 0xB04 to the default HW value of 0xC40 */
This reads to me like 0xC40 is hard coded in the GuC. I would prefer 
something like "On RC6 exit, GuC will write register 0xB04 with the 
value provided. The default value for 0xB04 in bspec is 0xC40, so use that."

John.

> +	if (XE_WA(gt, 13011645652))
> +		guc_waklv_enable_one_word(ads,
> +					  GUC_WA_KLV_NP_RD_WRITE_TO_CLEAR_RCSM_AT_CGP_LATE_RESTORE,
> +					  0xC40,
> +					  &offset, &remain);
> +
>   	size = guc_ads_waklv_size(ads) - remain;
>   	if (!size)
>   		return;
> diff --git a/drivers/gpu/drm/xe/xe_wa_oob.rules b/drivers/gpu/drm/xe/xe_wa_oob.rules
> index eb647d5a1e16..12fe88796a49 100644
> --- a/drivers/gpu/drm/xe/xe_wa_oob.rules
> +++ b/drivers/gpu/drm/xe/xe_wa_oob.rules
> @@ -26,3 +26,4 @@
>   		MEDIA_VERSION(2000)
>   16022287689	GRAPHICS_VERSION(2001)
>   		GRAPHICS_VERSION(2004)
> +13011645652	GRAPHICS_VERSION(2004)