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

[Patrik Jakobsson <patrik.jakobsson@linux.intel.com>]

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)
 #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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