Re: [Intel-gfx] [PATCH 1/2] drm/i915/dmc: Use RUNTIME_INFO->step for DMC

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 01 Jul 2021, Anusha Srivatsa <anusha.srivatsa@intel.com> wrote:
> On the dmc side,we maintain a lookup table with different display
> stepping-substepping combinations.
>
> Instead of adding new table for every new platform, lets ues
> the stepping info from RUNTIME_INFO(dev_priv)->step
>
> v2: Add stepping table for older platforms in intel_step.c (Lucas)
>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dmc.c | 117 +++++++++++++++--------

The changes here...

>  drivers/gpu/drm/i915/intel_step.c        |  41 ++++++++
>  drivers/gpu/drm/i915/intel_step.h        |   7 ++

...should be separate from, and depend on, the changes here. Please
don't try to do too much in one patch. Smaller is better.

>  3 files changed, 126 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
> index f8789d4543bf..df888a3d086e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dmc.c
> +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
> @@ -247,50 +247,89 @@ bool intel_dmc_has_payload(struct drm_i915_private *i915)
>  	return i915->dmc.dmc_info[DMC_FW_MAIN].payload;
>  }
>  
> -static const struct stepping_info skl_stepping_info[] = {
> -	{'A', '0'}, {'B', '0'}, {'C', '0'},
> -	{'D', '0'}, {'E', '0'}, {'F', '0'},
> -	{'G', '0'}, {'H', '0'}, {'I', '0'},
> -	{'J', '0'}, {'K', '0'}
> -};
> -
> -static const struct stepping_info bxt_stepping_info[] = {
> -	{'A', '0'}, {'A', '1'}, {'A', '2'},
> -	{'B', '0'}, {'B', '1'}, {'B', '2'}
> -};
> -
> -static const struct stepping_info icl_stepping_info[] = {
> -	{'A', '0'}, {'A', '1'}, {'A', '2'},
> -	{'B', '0'}, {'B', '2'},
> -	{'C', '0'}
> -};
> -
>  static const struct stepping_info no_stepping_info = { '*', '*' };
> +struct stepping_info *display_step;
>  
> -static const struct stepping_info *
> +static struct stepping_info *
>  intel_get_stepping_info(struct drm_i915_private *dev_priv)
>  {
> -	const struct stepping_info *si;
> -	unsigned int size;
> -
> -	if (IS_ICELAKE(dev_priv)) {
> -		size = ARRAY_SIZE(icl_stepping_info);
> -		si = icl_stepping_info;
> -	} else if (IS_SKYLAKE(dev_priv)) {
> -		size = ARRAY_SIZE(skl_stepping_info);
> -		si = skl_stepping_info;
> -	} else if (IS_BROXTON(dev_priv)) {
> -		size = ARRAY_SIZE(bxt_stepping_info);
> -		si = bxt_stepping_info;
> -	} else {
> -		size = 0;
> -		si = NULL;
> +	struct intel_step_info step = RUNTIME_INFO(dev_priv)->step;
> +
> +	switch (step.display_step) {
> +	case STEP_A0:
> +		display_step->stepping = 'A';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_A1:
> +		display_step->stepping = 'A';
> +		display_step->substepping = '1';
> +		break;
> +	case STEP_A2:
> +		display_step->stepping = 'A';
> +		display_step->substepping = '2';
> +		break;
> +	case STEP_B0:
> +		display_step->stepping = 'B';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_B1:
> +		display_step->stepping = 'B';
> +		display_step->substepping = '1';
> +		break;
> +	case STEP_B2:
> +		display_step->stepping = 'B';
> +		display_step->substepping = '2';
> +		break;
> +	case STEP_C0:
> +		display_step->stepping = 'C';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_C1:
> +		display_step->stepping = 'C';
> +		display_step->substepping = '1';
> +		break;
> +	case STEP_D0:
> +		display_step->stepping = 'D';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_D1:
> +		display_step->stepping = 'D';
> +		display_step->substepping = '1';
> +		break;
> +	case STEP_E0:
> +		display_step->stepping = 'E';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_F0:
> +		display_step->stepping = 'F';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_G0:
> +		display_step->stepping = 'G';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_H0:
> +		display_step->stepping = 'H';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_I0:
> +		display_step->stepping = 'I';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_J0:
> +		display_step->stepping = 'J';
> +		display_step->substepping = '0';
> +		break;
> +	case STEP_K0:
> +		display_step->stepping = 'K';
> +		display_step->substepping = '0';
> +		break;
> +	default:
> +		display_step->stepping = '*';
> +		display_step->substepping = '*';
> +		break;
>  	}
> -
> -	if (INTEL_REVID(dev_priv) < size)
> -		return si + INTEL_REVID(dev_priv);
> -
> -	return &no_stepping_info;
> +	return display_step;
>  }
>  
>  static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/intel_step.c b/drivers/gpu/drm/i915/intel_step.c
> index ba9479a67521..c8542161c5d0 100644
> --- a/drivers/gpu/drm/i915/intel_step.c
> +++ b/drivers/gpu/drm/i915/intel_step.c
> @@ -15,6 +15,38 @@
>  
>  
>  /* FIXME: what about REVID_E0 */

So that comment was next to kbl_revids, and this makes it meaningless.

> +static const struct intel_step_info bxt_revid_step_tbl[] = {

Please just call them "bxt_revids" or "bxt_steps" or something simple. I
meant to clean up all the other names too, they're a bit excessive.

> +	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
> +	[1] = { .gt_step = STEP_A1, .display_step = STEP_A1 },
> +	[2] = { .gt_step = STEP_A2, .display_step = STEP_A2 },
> +	[6] = { .gt_step = STEP_B0, .display_step = STEP_B0 },
> +	[7] = { .gt_step = STEP_B1, .display_step = STEP_B1 },
> +	[8] = { .gt_step = STEP_B2, .display_step = STEP_B2 },
> +};

We might want to add something like this:

@@ -112,5 +112,8 @@ void intel_step_init(struct drm_i915_private *i915)
 	if (drm_WARN_ON(&i915->drm, step.gt_step == STEP_NONE))
 		return;
 
+	if (step.display_step == STEP_NONE)
+		step.display_step = step.gt_step;
+
 	RUNTIME_INFO(i915)->step = step;
 }

So that we could just initialize .gt_step when the .display_step matches
the .gt_step, and we could avoid the repetition. This wasn't useful for
the platforms currently added, because they actually have the
differences.

This can also be left for future cleanup.

> +
> +

Superfluous newline.

> +static const struct intel_step_info skl_revid_step_tbl[] = {
> +	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
> +	[1] = { .gt_step = STEP_B0, .display_step = STEP_B0 },
> +	[2] = { .gt_step = STEP_C0, .display_step = STEP_C0 },
> +	[3] = { .gt_step = STEP_D0, .display_step = STEP_D0 },
> +	[4] = { .gt_step = STEP_E0, .display_step = STEP_E0 },
> +	[5] = { .gt_step = STEP_F0, .display_step = STEP_F0 },
> +	[6] = { .gt_step = STEP_G0, .display_step = STEP_G0 },
> +	[7] = { .gt_step = STEP_H0, .display_step = STEP_H0 },
> +	[8] = { .gt_step = STEP_I0, .display_step = STEP_I0 },
> +	[9] = { .gt_step = STEP_J0, .display_step = STEP_J0 },

skl_stepping_info in intel_dmc.c has K0, this one doesn't.

> +};
> +
> +static const struct intel_step_info icl_revid_step_tbl[] = {
> +	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
> +	[3] = { .gt_step = STEP_B0, .display_step = STEP_B0 },
> +	[4] = { .gt_step = STEP_B2, .display_step = STEP_B2 },
> +	[5] = { .gt_step = STEP_C0, .display_step = STEP_C0 },
> +	[6] = { .gt_step = STEP_C1, .display_step = STEP_C1 },
> +	[7] = { .gt_step = STEP_D0, .display_step = STEP_D0 },

icl_stepping_info in intel_dmc.c has A1 and A2, this one doesn't. This
one has C1 and D0, the one in intel_dmc.c doesn't.

> +};
> +
>  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 +108,15 @@ 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_ICELAKE(i915)) {
> +		revids = icl_revid_step_tbl;
> +		size = ARRAY_SIZE(icl_revid_step_tbl);
> +	} else if (IS_SKYLAKE(i915)) {
> +		revids = skl_revid_step_tbl;
> +		size = ARRAY_SIZE(skl_revid_step_tbl);
> +	} else if (IS_BROXTON(i915)) {
> +		revids = bxt_revid_step_tbl;
> +		size = ARRAY_SIZE(bxt_revid_step_tbl);

Doing this should be accompanied by:

* Removing *all* ICL_REVID_*, SKL_REVID_* and BXT_REVID_* macros from
  i915_drv.h.

* Converting IS_ICL_REVID(), IS_SKL_REVID(), and IS_BXT_REVID() to
  IS_{ICL,SKL,KBL}_{GT,DISPLAY}_STEP().

* And making their references use the generic STEP_* macros.

These changes should probably be done on a platform by platform basis,
just in case we hit any issues. This needs to be trivial to bisect and
backtrack as needed.

We currently have two schemes just for transition; we do not want to
have two schemes for a single platform effective at the same time.


BR,
Jani.

>  	}
>  
>  	/* 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..1bffa41f2660 100644
> --- a/drivers/gpu/drm/i915/intel_step.h
> +++ b/drivers/gpu/drm/i915/intel_step.h
> @@ -22,15 +22,22 @@ struct intel_step_info {
>  enum intel_step {
>  	STEP_NONE = 0,
>  	STEP_A0,
> +	STEP_A1,
>  	STEP_A2,
>  	STEP_B0,
>  	STEP_B1,
> +	STEP_B2,
>  	STEP_C0,
> +	STEP_C1,
>  	STEP_D0,
>  	STEP_D1,
>  	STEP_E0,
>  	STEP_F0,
>  	STEP_G0,
> +	STEP_H0,
> +	STEP_I0,
> +	STEP_J0,
> +	STEP_K0,
>  	STEP_FUTURE,
>  	STEP_FOREVER,
>  };

-- 
Jani Nikula, Intel Open Source Graphics Center
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