On 8/28/2019 12:40 AM, Animesh Manna wrote:
Batch buffer will be created through dsb-reg-write function which can have
single/multiple request based on usecase and once the buffer is ready
commit function will trigger the execution of the batch buffer. All
the registers will be updated simultaneously.

v1: Initial version.
v2: Optimized code few places. (Chris)

Cc: Imre Deak <imre.d...@intel.com>
Cc: Jani Nikula <jani.nik...@intel.com>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Signed-off-by: Animesh Manna <animesh.ma...@intel.com>
---
  drivers/gpu/drm/i915/display/intel_dsb.c | 42 ++++++++++++++++++++++++
  drivers/gpu/drm/i915/display/intel_dsb.h |  1 +
  2 files changed, 43 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c 
b/drivers/gpu/drm/i915/display/intel_dsb.c
index 2d6e78868f2d..bc1734072f34 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -214,3 +214,45 @@ void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t 
reg, u32 val)
                                DSB_OPCODE_SHIFT) | DSB_BYTE_EN |
                                i915_mmio_reg_offset(reg);
  }
+
+void intel_dsb_commit(struct intel_dsb *dsb)
+{
+       struct intel_crtc *crtc = dsb->crtc;
+       struct drm_device *dev = crtc->base.dev;
+       struct drm_i915_private *dev_priv = to_i915(dev);
+       enum pipe pipe = crtc->pipe;
+       u32 tail;
+
+       if (!dsb->free_pos)
+               return;
How would the user know if DSB commit failed, and it has to retry ? should we add a return value ?
+
+       if (!intel_dsb_enable_engine(dsb))
+               goto reset;
+
+       if (is_dsb_busy(dsb)) {
+               DRM_DEBUG_KMS("HEAD_PTR write failed - dsb engine is busy.\n");
+               goto reset;
+       }
+       I915_WRITE(DSB_HEAD(pipe, dsb->id), i915_ggtt_offset(dsb->vma));
+
+       tail = ALIGN(dsb->free_pos * 4, CACHELINE_BYTES);
+       if (tail > dsb->free_pos * 4)
+               memset(&dsb->cmd_buf[dsb->free_pos], 0,
+                      (tail - dsb->free_pos * 4));
+
+       if (is_dsb_busy(dsb)) {
+               DRM_DEBUG_KMS("TAIL_PTR write failed - dsb engine is busy.\n");
+               goto reset;
+       }
a space here will look good, and aligned to above.
+       DRM_DEBUG_KMS("DSB execution started - head 0x%x, tail 0x%x\n",
+                     i915_ggtt_offset(dsb->vma), tail);
+       I915_WRITE(DSB_TAIL(pipe, dsb->id), i915_ggtt_offset(dsb->vma) + tail);
+       if (wait_for(!is_dsb_busy(dsb), 1)) {
This time limit of 1 is bspec recommended, or its by experience ?
+               DRM_ERROR("Timed out waiting for DSB workload completion.\n");
+               goto reset;
+       }
+
+reset:
+       dsb->free_pos = 0;
reset is just doing dsb->free_pos = 0; is that enough ? I think we need to do a complete reset of the buffer memset(dsb->buffer, 0) or something similar, else batch buffer will contain garbage values from previous weites.
+       intel_dsb_disable_engine(dsb);
We still want to return a -ve value to indicate the write failed.
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h 
b/drivers/gpu/drm/i915/display/intel_dsb.h
index c848747f52d9..f5d1f1bedc12 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.h
+++ b/drivers/gpu/drm/i915/display/intel_dsb.h
@@ -44,5 +44,6 @@ void intel_dsb_put(struct intel_dsb *dsb);
  void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val);
  void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
                                 u32 val);
+void intel_dsb_commit(struct intel_dsb *dsb);
#endif
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