Re: [PATCH v3 2/2] drm/xe/lnl: Enable GuC Wa_14019882105

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 25.03.2024 16:04, Badal Nilawar wrote:
> Enable GuC Wa_14019882105 to block interrupts during C6 flow
> when the memory path has been blocked
> 
> v2: Make helper function generic and name it as
>     guc_waklv_enable_simple (John Harrison)
> v3: Make warning descriptive (John Harrison)
> 
> Cc: John Harrison <john.harrison@intel.com>
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> ---
>  drivers/gpu/drm/xe/abi/guc_klvs_abi.h |  7 +++++
>  drivers/gpu/drm/xe/xe_guc_ads.c       | 41 +++++++++++++++++++++------
>  drivers/gpu/drm/xe/xe_wa_oob.rules    |  1 +
>  3 files changed, 40 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/abi/guc_klvs_abi.h b/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> index 0400bc0fccdc..5dd45e06f0b6 100644
> --- a/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> +++ b/drivers/gpu/drm/xe/abi/guc_klvs_abi.h
> @@ -319,4 +319,11 @@ enum  {
>  #define GUC_KLV_VF_CFG_BEGIN_CONTEXT_ID_KEY	0x8a0b
>  #define GUC_KLV_VF_CFG_BEGIN_CONTEXT_ID_LEN	1u
>  
> +/*
> + * Workaround keys:
> + */
> +enum xe_guc_klv_ids {
> +	GUC_WORKAROUND_KLV_BLOCK_INTERRUPTS_WHEN_MGSR_BLOCKED				= 0x9002,

how should we know the LEN of the particular W/A KLV ?
as this is the ABI header, IMO we should define that here along the KEY

> +};
> +
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_guc_ads.c b/drivers/gpu/drm/xe/xe_guc_ads.c
> index a98344a0ff4b..633e5fd9c738 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ads.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ads.c
> @@ -7,6 +7,8 @@
>  
>  #include <drm/drm_managed.h>
>  
> +#include <generated/xe_wa_oob.h>
> +
>  #include "regs/xe_engine_regs.h"
>  #include "regs/xe_gt_regs.h"
>  #include "regs/xe_guc_regs.h"
> @@ -19,6 +21,7 @@
>  #include "xe_map.h"
>  #include "xe_mmio.h"
>  #include "xe_platform_types.h"
> +#include "xe_wa.h"
>  
>  /* Slack of a few additional entries per engine */
>  #define ADS_REGSET_EXTRA_MAX	8
> @@ -279,23 +282,43 @@ static size_t calculate_golden_lrc_size(struct xe_guc_ads *ads)
>  	return total_size;
>  }
>  
> +static void guc_waklv_enable_simple(struct xe_guc_ads *ads,
> +				    enum xe_guc_klv_ids klv_id, u32 *offset, u32 *remain)
> +{
> +	u32 size;
> +	u32 klv_entry[] = {
> +		/* 16:16 key/length */

drop this comment, code is self explanatory

> +		FIELD_PREP(GUC_KLV_0_KEY, klv_id) |
> +		FIELD_PREP(GUC_KLV_0_LEN, 0),
> +		/* 0 dwords data */
> +	};

you can define size here:

		u32 size = sizeof(klv_entry);

> +
> +	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);

this looks like our programming error so xe_gt_assert() should be
sufficient as we don't expect this ever happen in production

but if you want to keep the WARN then use xe_gt_WARN() instead

> +	} 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_init(struct xe_guc_ads *ads)
>  {
> +	struct xe_gt *gt = ads_to_gt(ads);
>  	u64 addr_ggtt;
>  	u32 offset, remain, size;
>  
>  	offset = guc_ads_waklv_offset(ads);
>  	remain = guc_ads_waklv_size(ads);
>  
> -	/*
> -	 * Add workarounds here:
> -	 *
> -	 * if (want_wa_<name>) {
> -	 *      size = guc_waklv_<name>(guc, offset, remain);
> -	 *      offset += size;
> -	 *      remain -= size;
> -	 * }
> -	 */
> +	if (XE_WA(gt, 14019882105))
> +		guc_waklv_enable_simple(ads,
> +					GUC_WORKAROUND_KLV_BLOCK_INTERRUPTS_WHEN_MGSR_BLOCKED,
> +					&offset, &remain);

hmm, it looks that your implementation here in patch 2/2 is different
than suggested one in patch 1/2

>  
>  	size = guc_ads_waklv_size(ads) - remain;
>  	if (!size)
> diff --git a/drivers/gpu/drm/xe/xe_wa_oob.rules b/drivers/gpu/drm/xe/xe_wa_oob.rules
> index 48cdba1cbf95..a8d15f004b6c 100644
> --- a/drivers/gpu/drm/xe/xe_wa_oob.rules
> +++ b/drivers/gpu/drm/xe/xe_wa_oob.rules
> @@ -19,3 +19,4 @@
>  		GRAPHICS_VERSION_RANGE(1270, 1274)
>  		MEDIA_VERSION(1300)
>  		PLATFORM(DG2)
> +14019882105	GRAPHICS_VERSION(2004), GRAPHICS_STEP(A0, B0)