[Intel-gfx] [PATCH v4 03/11] drm/i915: Parse and set stepping for platforms with GMD

[Matt Roper]

On Thu, Sep 01, 2022 at 11:03:34PM -0700, Radhakrishna Sripada wrote:
> From: José Roberto de Souza <jose.souza at intel.com>
> 
> The GMD step field do not properly match the current stepping convention
> that we use(STEP_A0, STEP_A1, STEP_B0...).
> 
> One platform could have { arch = 12, rel = 70, step = 1 } and the
> actual stepping is STEP_B0 but without the translation of the step
> field would mean STEP_A1.
> That is why we will need to have gmd_to_intel_step tables for each IP.

The (unofficial) claim by the hardware team when GMD_ID was introduced
was that they planned to standardize stepping numbering going forward
such that they would leave space for up to four minor steppings between
each major stepping.  I.e., B0 is expected to be 0x4 on all future
platforms, C0 is expected to be 0x8, etc.

While I'm not super confident that they'll actually stick with that plan
forever (e.g., what happens if we wind up having an A5 stepping
someday?), it seems like we could at least start with that as our
initial assumption and write generic translation code for now; if/when
we encounter a platform that deviates, we can add a platform-specific
table for it at that time.


Matt

> 
> v2:
>  - Pass the updated ip version structure
> 
> Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan at intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_step.c | 60 +++++++++++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_step.c b/drivers/gpu/drm/i915/intel_step.c
> index 42b3133d8387..14ea103d6dab 100644
> --- a/drivers/gpu/drm/i915/intel_step.c
> +++ b/drivers/gpu/drm/i915/intel_step.c
> @@ -135,6 +135,48 @@ static const struct intel_step_info adlp_n_revids[] = {
>  	[0x0] = { COMMON_GT_MEDIA_STEP(A0), .display_step = STEP_D0 },
>  };
>  
> +struct gmd_to_intel_step {
> +	struct ip_version gmd;
> +	enum intel_step step;
> +};
> +
> +static const struct gmd_to_intel_step gmd_graphics_table[] = {
> +	{ .gmd.ver = 12, .gmd.rel = 70, .gmd.step = 0, .step = STEP_A0 },
> +	{ .gmd.ver = 12, .gmd.rel = 70, .gmd.step = 4, .step = STEP_B0 },
> +	{ .gmd.ver = 12, .gmd.rel = 71, .gmd.step = 0, .step = STEP_A0 },
> +	{ .gmd.ver = 12, .gmd.rel = 71, .gmd.step = 4, .step = STEP_B0 },
> +	{ .gmd.ver = 12, .gmd.rel = 73, .gmd.step = 0, .step = STEP_A0 },
> +	{ .gmd.ver = 12, .gmd.rel = 73, .gmd.step = 4, .step = STEP_B0 },
> +};
> +
> +static const struct gmd_to_intel_step gmd_media_table[] = {
> +	{ .gmd.ver = 13, .gmd.rel = 70, .gmd.step = 0, .step = STEP_A0 },
> +	{ .gmd.ver = 13, .gmd.rel = 70, .gmd.step = 4, .step = STEP_B0 },
> +};
> +
> +static const struct gmd_to_intel_step gmd_display_table[] = {
> +	{ .gmd.ver = 14, .gmd.rel = 0, .gmd.step = 0, .step = STEP_A0 },
> +	{ .gmd.ver = 14, .gmd.rel = 0, .gmd.step = 4, .step = STEP_B0 },
> +};
> +
> +static u8 gmd_to_intel_step(struct drm_i915_private *i915,
> +			    struct ip_version *gmd,
> +			    const struct gmd_to_intel_step *table,
> +			    int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++) {
> +		if (table[i].gmd.ver == gmd->ver &&
> +		    table[i].gmd.rel == gmd->rel &&
> +		    table[i].gmd.step == gmd->step)
> +			return table[i].step;
> +	}
> +
> +	drm_dbg(&i915->drm, "Using future steppings\n");
> +	return STEP_FUTURE;
> +}
> +
>  static void pvc_step_init(struct drm_i915_private *i915, int pci_revid);
>  
>  void intel_step_init(struct drm_i915_private *i915)
> @@ -144,6 +186,24 @@ void intel_step_init(struct drm_i915_private *i915)
>  	int revid = INTEL_REVID(i915);
>  	struct intel_step_info step = {};
>  
> +	if (HAS_GMD_ID(i915)) {
> +		step.graphics_step = gmd_to_intel_step(i915,
> +						       &RUNTIME_INFO(i915)->graphics.version,
> +						       gmd_graphics_table,
> +						       ARRAY_SIZE(gmd_graphics_table));
> +		step.media_step = gmd_to_intel_step(i915,
> +						    &RUNTIME_INFO(i915)->media.version,
> +						    gmd_media_table,
> +						    ARRAY_SIZE(gmd_media_table));
> +		step.display_step = gmd_to_intel_step(i915,
> +						      &RUNTIME_INFO(i915)->display.version,
> +						      gmd_display_table,
> +						      ARRAY_SIZE(gmd_display_table));
> +		RUNTIME_INFO(i915)->step = step;
> +
> +		return;
> +	}
> +
>  	if (IS_PONTEVECCHIO(i915)) {
>  		pvc_step_init(i915, revid);
>  		return;
> -- 
> 2.34.1
> 

-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation