[RFC v1] drm/i915: Add Exec param to control data port coherency.

[Tomasz Lis <tomasz.lis@intel.com>]

The patch adds a parameter to control the data port coherency functionality
on a per-exec call basis. When data port coherency flag value is different
than what it was in previous call for the context, a command to switch data
port coherency state is added before the buffer to be executed.

Bspec: 11419
---
 drivers/gpu/drm/i915/i915_drv.c            |  3 ++
 drivers/gpu/drm/i915/i915_gem_context.h    |  1 +
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 17 ++++++++++
 drivers/gpu/drm/i915/intel_lrc.c           | 53 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_lrc.h           |  3 ++
 include/uapi/drm/i915_drm.h                | 12 ++++++-
 6 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 3df5193..fcb3547 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -436,6 +436,9 @@ static int i915_getparam_ioctl(struct drm_device *dev, void *data,
 	case I915_PARAM_CS_TIMESTAMP_FREQUENCY:
 		value = 1000 * INTEL_INFO(dev_priv)->cs_timestamp_frequency_khz;
 		break;
+	case I915_PARAM_HAS_EXEC_DATA_PORT_COHERENCY:
+		value = (INTEL_GEN(dev_priv) >= 9);
+		break;
 	default:
 		DRM_DEBUG("Unknown parameter %d\n", param->param);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index 7854262..00aa309 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -118,6 +118,7 @@ struct i915_gem_context {
 #define CONTEXT_BANNABLE		3
 #define CONTEXT_BANNED			4
 #define CONTEXT_FORCE_SINGLE_SUBMISSION	5
+#define CONTEXT_DATA_PORT_COHERENT	6
 
 	/**
 	 * @hw_id: - unique identifier for the context
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 8c170db..f848f14 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2245,6 +2245,18 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 		eb.batch_flags |= I915_DISPATCH_RS;
 	}
 
+	if (args->flags & I915_EXEC_DATA_PORT_COHERENT) {
+		if (INTEL_GEN(eb.i915) < 9) {
+			DRM_DEBUG("Data Port Coherency is only allowed for Gen9 and above\n");
+			return -EINVAL;
+		}
+		if (eb.engine->class != RENDER_CLASS) {
+			DRM_DEBUG("Data Port Coherency is not available on %s\n",
+				 eb.engine->name);
+			return -EINVAL;
+		}
+	}
+
 	if (args->flags & I915_EXEC_FENCE_IN) {
 		in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
 		if (!in_fence)
@@ -2371,6 +2383,11 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 		goto err_batch_unpin;
 	}
 
+	/* Emit the switch of data port coherency state if needed */
+	err = intel_lr_context_modify_data_port_coherency(eb.request,
+			(args->flags & I915_EXEC_DATA_PORT_COHERENT) != 0);
+	GEM_WARN_ON(err);
+
 	if (in_fence) {
 		err = i915_request_await_dma_fence(eb.request, in_fence);
 		if (err < 0)
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 53f1c00..b847798 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -254,6 +254,59 @@ intel_lr_context_descriptor_update(struct i915_gem_context *ctx,
 	ce->lrc_desc = desc;
 }
 
+static int emit_set_data_port_coherency(struct i915_request *req, bool enable)
+{
+	u32 *cs;
+	i915_reg_t reg;
+
+	GEM_BUG_ON(req->engine->class != RENDER_CLASS);
+	GEM_BUG_ON(INTEL_GEN(req->i915) < 9);
+
+	cs = intel_ring_begin(req, 4);
+	if (IS_ERR(cs))
+		return PTR_ERR(cs);
+
+	if (INTEL_GEN(req->i915) >= 10)
+		reg = CNL_HDC_CHICKEN0;
+	else
+		reg = HDC_CHICKEN0;
+
+	*cs++ = MI_LOAD_REGISTER_IMM(1);
+	*cs++ = i915_mmio_reg_offset(reg);
+	/* Enabling coherency means disabling the bit which forces it off */
+	if (enable)
+		*cs++ = _MASKED_BIT_DISABLE(HDC_FORCE_NON_COHERENT);
+	else
+		*cs++ = _MASKED_BIT_ENABLE(HDC_FORCE_NON_COHERENT);
+	*cs++ = MI_NOOP;
+
+	intel_ring_advance(req, cs);
+
+	return 0;
+}
+
+int
+intel_lr_context_modify_data_port_coherency(struct i915_request *req,
+					bool enable)
+{
+	struct i915_gem_context *ctx = req->ctx;
+	int ret;
+
+	if (test_bit(CONTEXT_DATA_PORT_COHERENT, &ctx->flags) == enable)
+		return 0;
+
+	ret = emit_set_data_port_coherency(req, enable);
+
+	if (!ret) {
+		if (enable)
+			__set_bit(CONTEXT_DATA_PORT_COHERENT, &ctx->flags);
+		else
+			__clear_bit(CONTEXT_DATA_PORT_COHERENT, &ctx->flags);
+	}
+
+	return ret;
+}
+
 static struct i915_priolist *
 lookup_priolist(struct intel_engine_cs *engine,
 		struct i915_priotree *pt,
diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
index 59d7b86..c46b239 100644
--- a/drivers/gpu/drm/i915/intel_lrc.h
+++ b/drivers/gpu/drm/i915/intel_lrc.h
@@ -111,4 +111,7 @@ intel_lr_context_descriptor(struct i915_gem_context *ctx,
 	return ctx->engine[engine->id].lrc_desc;
 }
 
+int intel_lr_context_modify_data_port_coherency(struct i915_request *req,
+						bool enable);
+
 #endif /* _INTEL_LRC_H_ */
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 7f5634c..a5fed1f 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -529,6 +529,11 @@ typedef struct drm_i915_irq_wait {
  */
 #define I915_PARAM_CS_TIMESTAMP_FREQUENCY 51
 
+/* Query whether DRM_I915_GEM_EXECBUFFER2 supports the ability to switch
+ * Data Cache access into Data Port Coherency mode.
+ */
+#define I915_PARAM_HAS_EXEC_DATA_PORT_COHERENCY 52
+
 typedef struct drm_i915_getparam {
 	__s32 param;
 	/*
@@ -1048,7 +1053,12 @@ struct drm_i915_gem_execbuffer2 {
  */
 #define I915_EXEC_FENCE_ARRAY   (1<<19)
 
-#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_ARRAY<<1))
+/* Data Port Coherency capability will be switched before an exec call
+ * which has this flag different than previous call for the context.
+ */
+#define I915_EXEC_DATA_PORT_COHERENT   (1<<20)
+
+#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_DATA_PORT_COHERENT<<1))
 
 #define I915_EXEC_CONTEXT_ID_MASK	(0xffffffff)
 #define i915_execbuffer2_set_context_id(eb2, context) \
-- 
2.7.4

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