Re: [Intel-gfx] [PATCH] drm/i915: Tweaked Wa_14010685332 for PCHs used on gen11 platforms

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Oct 30, 2020 at 11:46:58AM +0530, Anshuman Gupta wrote:
> From: Bob Paauwe <bob.j.paauwe@intel.com>
> 
> The WA specifies that we need to toggle a SDE chicken bit on and then
> off as the final step in preparation for s0ix entry.
> 
>     Bspec: 33450
>     Bspec: 8402
> 
> However, something is happening after we toggle the bit that causes
> the WA to be invalidated. This makes dispcnlunit1_cp_xosc_clkreq
> active being already in s0ix state i.e SLP_S0 counter incremented.
> Tweaking the Wa_14010685332 by setting the bit on suspend and clearing
> it on resume turns down the dispcnlunit1_cp_xosc_clkreq.
> B.Spec has Documented this tweaked sequence of WA as an alternative.
> Let keep this tweaked WA for Gen11 platforms and keep untweaked WA for
> other platforms which never observed this issue.
> 
> v2 (MattR):
>  - Change the comment on the workaround to give PCH names rather than
>    platform names.  Although the bspec is setup to list workarounds by
>    platform, the hardware team has confirmed that the actual issue being
>    worked around here is something that was introduced back in the
>    Cannon Lake PCH and carried forward to subsequent PCH's.
>  - Extend the untweaked version of the workaround to include  PCH_CNP as
>    well.  Note that since PCH_CNP is used to represent CMP, this will
>    apply on CML and some variants of RKL too.
>  - Cap the untweaked version of the workaround so that it won't apply to
>    "fake" PCH's (i.e., DG1).  The issue we're working around really is
>    an issue in the PCH itself, not the South Display, so it shouldn't
>    apply when there isn't a real PCH.
> 
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Bob Paauwe <bob.j.paauwe@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  .../drm/i915/display/intel_display_power.c    | 21 +++++++++++++++++--
>  drivers/gpu/drm/i915/i915_irq.c               |  6 ++++--
>  2 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 689922480661..d2a6518329d7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -5858,17 +5858,34 @@ static void intel_power_domains_verify_state(struct drm_i915_private *i915)
>  
>  void intel_display_power_suspend_late(struct drm_i915_private *i915)
>  {
> -	if (INTEL_GEN(i915) >= 11 || IS_GEN9_LP(i915))
> +	u32 val;
> +
> +	if (INTEL_GEN(i915) >= 11 || IS_GEN9_LP(i915)) {
>  		bxt_enable_dc9(i915);
> -	else if (IS_HASWELL(i915) || IS_BROADWELL(i915))
> +		/* Tweaked Wa_14010685332:icp,jsp,mcc */
> +		if (INTEL_PCH_TYPE(i915) >= PCH_ICP && INTEL_PCH_TYPE(i915) <= PCH_MCC) {
> +			val = intel_de_read(i915, SOUTH_CHICKEN1);
> +			val |= SBCLK_RUN_REFCLK_DIS;
> +			intel_de_write(i915, SOUTH_CHICKEN1, val);

could we use intel_de_rmw here?

> +		}
> +	} else if (IS_HASWELL(i915) || IS_BROADWELL(i915)) {
>  		hsw_enable_pc8(i915);
> +	}
>  }
>  
>  void intel_display_power_resume_early(struct drm_i915_private *i915)
>  {
> +	u32 val;
> +
>  	if (INTEL_GEN(i915) >= 11 || IS_GEN9_LP(i915)) {
>  		gen9_sanitize_dc_state(i915);
>  		bxt_disable_dc9(i915);
> +		/* Tweaked Wa_14010685332:icp,jsp,mcc */
> +		if (INTEL_PCH_TYPE(i915) >= PCH_ICP && INTEL_PCH_TYPE(i915) <= PCH_MCC) {
> +			val = intel_de_read(i915, SOUTH_CHICKEN1);
> +			val &= ~SBCLK_RUN_REFCLK_DIS;
> +			intel_de_write(i915, SOUTH_CHICKEN1, val);

and here?

sorry for not having spotted that sooner.

> +		}
>  	} else if (IS_HASWELL(i915) || IS_BROADWELL(i915)) {
>  		hsw_disable_pc8(i915);
>  	}
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index dc33c96d741d..410c03624c6a 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -3055,8 +3055,10 @@ static void gen11_display_irq_reset(struct drm_i915_private *dev_priv)
>  	if (INTEL_PCH_TYPE(dev_priv) >= PCH_ICP)
>  		GEN3_IRQ_RESET(uncore, SDE);
>  
> -	/* Wa_14010685332:icl,jsl,ehl,tgl,rkl */
> -	if (INTEL_PCH_TYPE(dev_priv) >= PCH_ICP) {
> +	/* Wa_14010685332:cnp/cmp,tgp,adp */
> +	if (INTEL_PCH_TYPE(dev_priv) == PCH_CNP ||
> +	    (INTEL_PCH_TYPE(dev_priv) >= PCH_TGP &&
> +	     INTEL_PCH_TYPE(dev_priv) < PCH_DG1)) {
>  		intel_uncore_rmw(uncore, SOUTH_CHICKEN1,
>  				 SBCLK_RUN_REFCLK_DIS, SBCLK_RUN_REFCLK_DIS);
>  		intel_uncore_rmw(uncore, SOUTH_CHICKEN1,
> -- 
> 2.26.2
> 
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