[Intel-gfx] [PATCH v3] drm/i915/gt: Implement WA_1406941453

[Taylor, Clinton A]

CI failed with lost value on reset

<3> [300.632894] [drm:wa_verify [i915]] *ERROR* GT_REF workaround lost on before reset! (e18c=3020/0, expected 80008000)
<3> [300.665974] i915/intel_workarounds_live_selftests: live_gpu_reset_workarounds failed with error -3

I will move the W/A to the RCS engine.

Clint


-----Original Message-----
From: Matt Roper <matthew.d.roper at intel.com> 
Sent: Tuesday, August 25, 2020 3:11 PM
To: Taylor, Clinton A <clinton.a.taylor at intel.com>
Cc: Intel-gfx at lists.freedesktop.org; Atwood, Matthew S <matthew.s.atwood at intel.com>; Souza, Jose <jose.souza at intel.com>
Subject: Re: [PATCH v3] drm/i915/gt: Implement WA_1406941453
CI failed with 
On Tue, Aug 25, 2020 at 02:54:34PM -0700, clinton.a.taylor at intel.com wrote:
> From: Clint Taylor <clinton.a.taylor at intel.com>
> 
> Enable HW Default flip for small PL.
> 
> bspec: 52890
> bspec: 53508
> bspec: 53273
> 
> v2: rebase to drm-tip
> v3: move from ctx to gt workarounds. Remove whitelist.

I think we actually want to move this one to the rcs_engine_wa_init() since the register appears to be part of the render engine specifically.
Since this register doesn't hold its value across engine resets[*] we want to re-apply the workaround any time the RCS engine is reset.

[*] There's been a bit of ambiguity and confusion about what registers do/don't survive engine resets, but we're starting to get more clarity on that from the hardware teams now.  There's usually a field in the bspec's register description that says "GTIReset" --- if that says "DEV"
it's an engine register that should be handled in rcs_engine_wa_init (or xcs_engine_wa_init for other engine types), whereas if it says "BUS"
it's a GT register that should go in gt_workarounds_init.


Matt

> 
> Cc: Matt Atwood <matthew.s.atwood at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Cc: José Roberto de Souza <jose.souza at intel.com>
> Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 3 +++
>  drivers/gpu/drm/i915/i915_reg.h             | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c 
> b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index a3f72b75c61e..0aecb97fd41c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -1211,6 +1211,9 @@ gen12_gt_workarounds_init(struct drm_i915_private *i915,
>  			  struct i915_wa_list *wal)
>  {
>  	wa_init_mcr(i915, wal);
> +
> +	/* Wa_1406941453:gen12 */
> +	WA_SET_BIT_MASKED(GEN10_SAMPLER_MODE, ENABLE_SMALLPL);
>  }
>  
>  static void
> diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> b/drivers/gpu/drm/i915/i915_reg.h index ac691927e29d..ab4b1abd4364 
> 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9315,6 +9315,7 @@ enum {
>  #define   GEN11_LSN_UNSLCVC_GAFS_HALF_SF_MAXALLOC	(1 << 7)
>  
>  #define GEN10_SAMPLER_MODE		_MMIO(0xE18C)
> +#define   ENABLE_SMALLPL			REG_BIT(15)
>  #define   GEN11_SAMPLER_ENABLE_HEADLESS_MSG	REG_BIT(5)
>  
>  /* IVYBRIDGE DPF */
> --
> 2.28.0
> 

-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795