Re: [PATCH v3] drm/i915/skl/kbl: Add support for pipe fusing

[Damien Lespiau <damien.lespiau@intel.com>]

On Wed, Jan 20, 2016 at 03:31:20PM +0100, Patrik Jakobsson wrote:
> On SKL and KBL we can have pipe A/B/C disabled by fuse settings. The
> pipes must be fused in descending order (e.g. C, B+C, A+B+C). We simply
> decrease info->num_pipes if we find a valid fused out config.
> 
> v2: Don't store the pipe disabled mask in device info (Damien)
> 
> v3: Don't check FUSE_STRAP register for pipe c disabled
> 
> Cc: Damien Lespiau <damien.lespiau@intel.com>
> Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>

(listing the valid cases would have made things simpler?)

-- 
Damien

> ---
>  drivers/gpu/drm/i915/i915_dma.c | 31 +++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_reg.h |  3 +++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 44a896c..daaa67f 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -814,6 +814,37 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
>  			DRM_INFO("Display fused off, disabling\n");
>  			info->num_pipes = 0;
>  		}
> +	} else if (info->num_pipes > 0 && INTEL_INFO(dev)->gen == 9) {
> +		u32 dfsm = I915_READ(SKL_DFSM);
> +		u8 disabled_mask = 0;
> +		bool invalid;
> +		int num_bits;
> +
> +		if (dfsm & SKL_DFSM_PIPE_A_DISABLE)
> +			disabled_mask |= BIT(PIPE_A);
> +		if (dfsm & SKL_DFSM_PIPE_B_DISABLE)
> +			disabled_mask |= BIT(PIPE_B);
> +		if (dfsm & SKL_DFSM_PIPE_C_DISABLE)
> +			disabled_mask |= BIT(PIPE_C);
> +
> +		num_bits = hweight8(disabled_mask);
> +
> +		switch (disabled_mask) {
> +			case BIT(PIPE_A):
> +			case BIT(PIPE_B):
> +			case BIT(PIPE_A) | BIT(PIPE_B):
> +			case BIT(PIPE_A) | BIT(PIPE_C):
> +				invalid = true;
> +				break;
> +			default:
> +				invalid = false;
> +		}
> +
> +		if (num_bits > info->num_pipes || invalid)
> +			DRM_ERROR("invalid pipe fuse configuration: 0x%x\n",
> +				  disabled_mask);
> +		else
> +			info->num_pipes -= num_bits;
>  	}
>  
>  	/* Initialize slice/subslice/EU info */
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 556a458..c6e6a24 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5991,6 +5991,9 @@ enum skl_disp_power_wells {
>  #define SKL_DFSM_CDCLK_LIMIT_540	(1 << 23)
>  #define SKL_DFSM_CDCLK_LIMIT_450	(2 << 23)
>  #define SKL_DFSM_CDCLK_LIMIT_337_5	(3 << 23)
> +#define SKL_DFSM_PIPE_A_DISABLE		(1 << 30)
> +#define SKL_DFSM_PIPE_B_DISABLE		(1 << 21)
> +#define SKL_DFSM_PIPE_C_DISABLE		(1 << 28)
>  
>  #define FF_SLICE_CS_CHICKEN2			_MMIO(0x20e4)
>  #define  GEN9_TSG_BARRIER_ACK_DISABLE		(1<<8)
> -- 
> 2.5.0
> 
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