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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