Re: [Intel-xe] [PATCH 1/6] drm/xe/mocs: Drop unwanted TGL table

[Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>]

On 16.02.2023 15:17, Matt Roper wrote:
> TGL/RKL/ADLS/ADLP are all supposed to use the same MOCS table, with
> values defined in the bspec.  Any entries listed in the bspec as
> reserved/error/undefined should always be initialized to the most cached
> and least coherent setting possible so that any userspace accidentally
> referencing those undefined entries will only experience an increase in
> coherency if spec updates down the road start defining real values.
> 
> The TGL and gen12 tables that exist in the driver today are identical
> except that the TGL includes one additional (incorrect) setting for PAT
> index 1.  This is a holdover from i915 where the platform was enabled
> with an incorrect setting and by the time we noticed, it was too late to
> fix the table without breaking ABI compatibility (and on TGL we did
> indeed have some buggy userspace that was referencing the 'reserved'
> entry 1).  Since the Xe driver starts fresh with a clean slate on ABI,
> there's no need to repeat the mistakes of i915 here.
> 
> Bspec: 45101
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>

Regards,
Bala

> ---
>  drivers/gpu/drm/xe/xe_mocs.c | 46 ------------------------------------
>  1 file changed, 46 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_mocs.c b/drivers/gpu/drm/xe/xe_mocs.c
> index 86b966fffbe5..09adb69d1545 100644
> --- a/drivers/gpu/drm/xe/xe_mocs.c
> +++ b/drivers/gpu/drm/xe/xe_mocs.c
> @@ -247,47 +247,6 @@ struct xe_mocs_info {
>  		LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
>  		L3_1_UC)
>  
> -static const struct xe_mocs_entry tgl_mocs_desc[] = {
> -	/*
> -	 * NOTE:
> -	 * Reserved and unspecified MOCS indices have been set to (L3 + LCC).
> -	 * These reserved entries should never be used, they may be changed
> -	 * to low performant variants with better coherency in the future if
> -	 * more entries are needed. We are programming index XE_MOCS_PTE(1)
> -	 * only, __init_mocs_table() take care to program unused index with
> -	 * this entry.
> -	 */
> -	MOCS_ENTRY(XE_MOCS_PTE,
> -		   LE_0_PAGETABLE | LE_TC_0_PAGETABLE,
> -		   L3_1_UC),
> -	GEN11_MOCS_ENTRIES,
> -
> -	/* Implicitly enable L1 - HDC:L1 + L3 + LLC */
> -	MOCS_ENTRY(48,
> -		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
> -		   L3_3_WB),
> -	/* Implicitly enable L1 - HDC:L1 + L3 */
> -	MOCS_ENTRY(49,
> -		   LE_1_UC | LE_TC_1_LLC,
> -		   L3_3_WB),
> -	/* Implicitly enable L1 - HDC:L1 + LLC */
> -	MOCS_ENTRY(50,
> -		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
> -		   L3_1_UC),
> -	/* Implicitly enable L1 - HDC:L1 */
> -	MOCS_ENTRY(51,
> -		   LE_1_UC | LE_TC_1_LLC,
> -		   L3_1_UC),
> -	/* HW Special Case (CCS) */
> -	MOCS_ENTRY(60,
> -		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
> -		   L3_1_UC),
> -	/* HW Special Case (Displayable) */
> -	MOCS_ENTRY(61,
> -		   LE_1_UC | LE_TC_1_LLC,
> -		   L3_3_WB),
> -};
> -
>  static const struct xe_mocs_entry dg1_mocs_desc[] = {
>  	/* UC */
>  	MOCS_ENTRY(1, 0, L3_1_UC),
> @@ -422,11 +381,6 @@ static unsigned int get_mocs_settings(struct xe_device *xe,
>  		info->unused_entries_index = 5;
>  		break;
>  	case XE_TIGERLAKE:
> -		info->size  = ARRAY_SIZE(tgl_mocs_desc);
> -		info->table = tgl_mocs_desc;
> -		info->n_entries = GEN9_NUM_MOCS_ENTRIES;
> -		info->uc_index = 3;
> -		break;
>  	case XE_ALDERLAKE_S:
>  	case XE_ALDERLAKE_P:
>  		info->size  = ARRAY_SIZE(gen12_mocs_desc);
> -- 
> 2.39.1
>