[Intel-gfx] [PATCH 4/4] drm/i915/dg1: WA GPU hang at RCC

[Matt Roper]

On Tue, Mar 02, 2021 at 05:07:28PM -0800, Lucas De Marchi wrote:
> From: Zhen Han <zhen.han at intel.com>
> 
> GPU hangs at RCC. According to Wa_14012131227 we shouldn't have a hang
> due to RHWO, but that is what we are observing, even without media
> compressible render target. Feedback from HW engineers is to leave RHWO
> disabled.

"14012131227" isn't the correct workaround number; that's a
platform-specific identifier.  This should be referred to by its lineage
number 22011054531 which is common across all affected platforms.
>From a quick scan, it looks like this isn't just a DG1 workaround, but
also applies to at least TGL and ADL-S as well (and is pending for RKL).

I'm not sure we actually need this workaround in the kernel though.
We're already whitelisting this register for userspace to allow UMD's to
apply workarounds to it directly (and UMD's are already doing their own
programming of the register for Wa_1808121037).  So it may be best to
leave the handling of this additional bit to them as well, especially if
the desired handling doesn't quite match the officially documented
workaround text.


Matt

> 
> Cc: Jianjun Liu <Jianjun.liu at intel.com>
> Cc: Chuansheng Liu <chuansheng.liu at intel.com>
> Cc: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> Signed-off-by: Zhen Han <zhen.han at intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index e678fa8d2ab9..5235fb70a69a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -739,6 +739,17 @@ static void dg1_ctx_workarounds_init(struct intel_engine_cs *engine,
>  	       FF_MODE2,
>  	       FF_MODE2_GS_TIMER_MASK,
>  	       FF_MODE2_GS_TIMER_224, 0);
> +
> +	/*
> +	 * Wa_14012131227
> +	 *
> +	 * Although the WA is described as causing corruption when using media
> +	 * compressible render target, leaving RHWO enabled is also causing
> +	 * gpu hang when using multiple concurrent render and media workloads.
> +	 * Disable it completely for now.
> +	 */
> +	wa_masked_en(wal, GEN7_COMMON_SLICE_CHICKEN1,
> +		     GEN9_RHWO_OPTIMIZATION_DISABLE);
>  }
>  
>  static void
> -- 
> 2.30.1
> 
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-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795