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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Jan 18, 2016 at 03:11:57PM +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). There are
> several registers that can contain fuse settings so to simplify things
> we keep around a mask in device info with bits for each disabled pipe.
> This will also come in handy if the rule about the descending order is
> changed on future platforms.
> 
> Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 34 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_drv.h |  1 +
>  drivers/gpu/drm/i915/i915_reg.h |  4 ++++
>  3 files changed, 39 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 988a380..2e9d47d 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -814,6 +814,40 @@ 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 fuse_strap = I915_READ(FUSE_STRAP);
> +		u32 dfsm = I915_READ(SKL_DFSM);
> +		bool invalid;
> +		int num_bits;
> +
> +		if (dfsm & SKL_DFSM_PIPE_A_DISABLE)
> +			info->pipe_disabled_mask |= BIT(PIPE_A);
> +		if (dfsm & SKL_DFSM_PIPE_B_DISABLE)
> +			info->pipe_disabled_mask |= BIT(PIPE_B);
> +		if (dfsm & SKL_DFSM_PIPE_C_DISABLE)
> +			info->pipe_disabled_mask |= BIT(PIPE_C);
> +
> +		if (fuse_strap & SKL_DISPLAY_PIPE_C_DISABLE)
> +			info->pipe_disabled_mask |= BIT(PIPE_C);
> +
> +		num_bits = hweight8(info->pipe_disabled_mask);
> +
> +		switch (info->pipe_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",
> +				  info->pipe_disabled_mask);
> +		else
> +			info->num_pipes -= num_bits;
>  	}
>  
>  	/* Initialize slice/subslice/EU info */
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index f0f75d7..2b4783c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -792,6 +792,7 @@ struct intel_device_info {
>  	u8 num_pipes:3;
>  	u8 num_sprites[I915_MAX_PIPES];
>  	u8 gen;
> +	u8 pipe_disabled_mask;
>  	u8 ring_mask; /* Rings supported by the HW */
>  	DEV_INFO_FOR_EACH_FLAG(DEFINE_FLAG, SEP_SEMICOLON);
>  	/* Register offsets for the various display pipes and transcoders */
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 7510d508..72f07e6 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5940,6 +5940,7 @@ enum skl_disp_power_wells {
>  #define  ILK_INTERNAL_GRAPHICS_DISABLE	(1 << 31)
>  #define  ILK_INTERNAL_DISPLAY_DISABLE	(1 << 30)
>  #define  ILK_DISPLAY_DEBUG_DISABLE	(1 << 29)
> +#define  SKL_DISPLAY_PIPE_C_DISABLE	(1 << 28)

Maybe you want to go review the other patch that wants to add this bit?

>  #define  ILK_HDCP_DISABLE		(1 << 25)
>  #define  ILK_eDP_A_DISABLE		(1 << 24)
>  #define  HSW_CDCLK_LIMIT		(1 << 24)
> @@ -5986,6 +5987,9 @@ 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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-- 
Ville Syrjälä
Intel OTC
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