Re: [Intel-gfx] [PATCH v2 03/12] drm/i915/skl: Use revid->stepping tables

["Srivatsa, Anusha" <anusha.srivatsa@intel.com>]

> -----Original Message-----
> From: Roper, Matthew D <matthew.d.roper@intel.com>
> Sent: Friday, July 9, 2021 8:37 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Srivatsa, Anusha <anusha.srivatsa@intel.com>; Roper, Matthew D
> <matthew.d.roper@intel.com>
> Subject: [PATCH v2 03/12] drm/i915/skl: Use revid->stepping tables
> 
> Switch SKL to use a revid->stepping table as we're trying to do on all
> platforms going forward.  Also drop the preproduction revisions and add the
> newer steppings we hadn't already handled.
> 
> Note that SKL has a case where a newer revision ID corresponds to an older
> GT/disp stepping (0x9 -> STEP_J0, 0xA -> STEP_I1).  Also, the lack of a revision
> ID 0x8 in the table is intentional and not an oversight.
> We'll re-write the KBL-specific comment to make it clear that these kind of
> quirks are expected.
> 
> v2:
>  - Since GT and display steppings are always identical on SKL use a
>    macro to set both values at once in a more readable manner.  (Anusha)
>  - Drop preproduction steppings.
> 
> Bspec: 13626
> Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c |  2 +-
>  drivers/gpu/drm/i915/i915_drv.h             | 11 +-------
>  drivers/gpu/drm/i915/intel_step.c           | 30 +++++++++++++++++----
>  drivers/gpu/drm/i915/intel_step.h           |  4 +++
>  4 files changed, 31 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index d9a5a445ceec..6dfd564e078f 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -883,7 +883,7 @@ skl_gt_workarounds_init(struct drm_i915_private
> *i915, struct i915_wa_list *wal)
>  		    GEN8_EU_GAUNIT_CLOCK_GATE_DISABLE);
> 
>  	/* WaInPlaceDecompressionHang:skl */
> -	if (IS_SKL_REVID(i915, SKL_REVID_H0, REVID_FOREVER))
> +	if (IS_SKL_GT_STEP(i915, STEP_H0, STEP_FOREVER))
>  		wa_write_or(wal,
>  			    GEN9_GAMT_ECO_REG_RW_IA,
>  			    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h index c4747f4407ef..f30499ed6787
> 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1515,16 +1515,7 @@ IS_SUBPLATFORM(const struct drm_i915_private
> *i915,  #define IS_TGL_Y(dev_priv) \
>  	IS_SUBPLATFORM(dev_priv, INTEL_TIGERLAKE,
> INTEL_SUBPLATFORM_ULX)
> 
> -#define SKL_REVID_A0		0x0
> -#define SKL_REVID_B0		0x1
> -#define SKL_REVID_C0		0x2
> -#define SKL_REVID_D0		0x3
> -#define SKL_REVID_E0		0x4
> -#define SKL_REVID_F0		0x5
> -#define SKL_REVID_G0		0x6
> -#define SKL_REVID_H0		0x7
> -
> -#define IS_SKL_REVID(p, since, until) (IS_SKYLAKE(p) && IS_REVID(p, since,
> until))
> +#define IS_SKL_GT_STEP(p, since, until) (IS_SKYLAKE(p) && IS_GT_STEP(p,
> +since, until))
> 
>  #define BXT_REVID_A0		0x0
>  #define BXT_REVID_A1		0x1
> diff --git a/drivers/gpu/drm/i915/intel_step.c
> b/drivers/gpu/drm/i915/intel_step.c
> index 93ccd42f2514..69c928b046e8 100644
> --- a/drivers/gpu/drm/i915/intel_step.c
> +++ b/drivers/gpu/drm/i915/intel_step.c
> @@ -7,14 +7,31 @@
>  #include "intel_step.h"
> 
>  /*
> - * KBL revision ID ordering is bizarre; higher revision ID's map to lower
> - * steppings in some cases.  So rather than test against the revision ID
> - * directly, let's map that into our own range of increasing ID's that we
> - * can test against in a regular manner.
> + * Some platforms have unusual ways of mapping PCI revision ID to
> + GT/display
> + * steppings.  E.g., in some cases a higher PCI revision may translate
> + to a
> + * lower stepping of the GT and/or display IP.  This file provides
> + lookup
> + * tables to map the PCI revision into a standard set of stepping
> + values that
> + * can be compared numerically.
> + *
> + * Also note that some revisions/steppings may have been set aside as
> + * placeholders but never materialized in real hardware; in those cases
> + there
> + * may be jumps in the revision IDs or stepping values in the tables below.
>   */
> 
> +/*
> + * Some platforms always have the same stepping value for GT and
> +display;
> + * use a macro to define these to make it easier to identify the
> +platforms
> + * where the two steppings can deviate.
> + */
> +#define COMMON_STEPPING(x)  .gt_step = STEP_##x, .display_step =
> +STEP_##x
> +
> +static const struct intel_step_info skl_revids[] = {
> +	[0x6] = { COMMON_STEPPING(G0) },
> +	[0x7] = { COMMON_STEPPING(H0) },
> +	[0x9] = { COMMON_STEPPING(J0) },
> +	[0xA] = { COMMON_STEPPING(I1) },
> +};
> 
> -/* FIXME: what about REVID_E0 */
>  static const struct intel_step_info kbl_revids[] = {
>  	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
>  	[1] = { .gt_step = STEP_B0, .display_step = STEP_B0 }, @@ -76,6 +93,9
> @@ void intel_step_init(struct drm_i915_private *i915)
>  	} else if (IS_KABYLAKE(i915)) {
>  		revids = kbl_revids;
>  		size = ARRAY_SIZE(kbl_revids);
> +	} else if (IS_SKYLAKE(i915)) {
> +		revids = skl_revids;
> +		size = ARRAY_SIZE(skl_revids);
>  	}
> 
>  	/* Not using the stepping scheme for the platform yet. */ diff --git
> a/drivers/gpu/drm/i915/intel_step.h b/drivers/gpu/drm/i915/intel_step.h
> index 958a8bb5d677..88a77159703e 100644
> --- a/drivers/gpu/drm/i915/intel_step.h
> +++ b/drivers/gpu/drm/i915/intel_step.h
> @@ -31,6 +31,10 @@ enum intel_step {
>  	STEP_E0,
>  	STEP_F0,
>  	STEP_G0,
> +	STEP_H0,
> +	STEP_I0,
> +	STEP_I1,
> +	STEP_J0,
>  	STEP_FUTURE,
>  	STEP_FOREVER,
>  };
> --
> 2.25.4

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