[PATCH 10/14] drm/i915/dsb: Introduce intel_dsb_chain()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

In order to handle the DEwake tricks without involving
the CPU we need a mechanism by which one DSB can start
another one. Add a basic function to do so. We'll extend
it later with additional code to actually deal with
DEwake.

Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 42 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dsb.h |  3 ++
 2 files changed, 45 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c 
b/drivers/gpu/drm/i915/display/intel_dsb.c
index 092cf082ac39..4c0519c41f16 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -502,6 +502,48 @@ static u32 dsb_error_int_en(struct intel_display *display)
        return errors;
 }
 
+static void _intel_dsb_chain(struct intel_atomic_state *state,
+                            struct intel_dsb *dsb,
+                            struct intel_dsb *chained_dsb,
+                            u32 ctrl)
+{
+       struct intel_display *display = to_intel_display(state->base.dev);
+       struct intel_crtc *crtc = dsb->crtc;
+       enum pipe pipe = crtc->pipe;
+       u32 tail;
+
+       if (drm_WARN_ON(display->drm, dsb->id == chained_dsb->id))
+               return;
+
+       tail = chained_dsb->free_pos * 4;
+       if (drm_WARN_ON(display->drm, !IS_ALIGNED(tail, CACHELINE_BYTES)))
+               return;
+
+       intel_dsb_reg_write(dsb, DSB_CTRL(pipe, chained_dsb->id),
+                           ctrl | DSB_ENABLE);
+
+       intel_dsb_reg_write(dsb, DSB_CHICKEN(pipe, chained_dsb->id),
+                           dsb_chicken(state, crtc));
+
+       intel_dsb_reg_write(dsb, DSB_INTERRUPT(pipe, chained_dsb->id),
+                           dsb_error_int_status(display) | DSB_PROG_INT_STATUS 
|
+                           dsb_error_int_en(display));
+
+       intel_dsb_reg_write(dsb, DSB_HEAD(pipe, chained_dsb->id),
+                           
intel_dsb_buffer_ggtt_offset(&chained_dsb->dsb_buf));
+
+       intel_dsb_reg_write(dsb, DSB_TAIL(pipe, chained_dsb->id),
+                           intel_dsb_buffer_ggtt_offset(&chained_dsb->dsb_buf) 
+ tail);
+}
+
+void intel_dsb_chain(struct intel_atomic_state *state,
+                    struct intel_dsb *dsb,
+                    struct intel_dsb *chained_dsb)
+{
+       _intel_dsb_chain(state, dsb, chained_dsb,
+                        0);
+}
+
 static void _intel_dsb_commit(struct intel_dsb *dsb, u32 ctrl,
                              int hw_dewake_scanline)
 {
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h 
b/drivers/gpu/drm/i915/display/intel_dsb.h
index d0737cefb393..e59fd7da0fc0 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.h
+++ b/drivers/gpu/drm/i915/display/intel_dsb.h
@@ -45,6 +45,9 @@ void intel_dsb_wait_scanline_in(struct intel_atomic_state 
*state,
 void intel_dsb_wait_scanline_out(struct intel_atomic_state *state,
                                 struct intel_dsb *dsb,
                                 int lower, int upper);
+void intel_dsb_chain(struct intel_atomic_state *state,
+                    struct intel_dsb *dsb,
+                    struct intel_dsb *chained_dsb);
 
 void intel_dsb_commit(struct intel_dsb *dsb,
                      bool wait_for_vblank);
-- 
2.44.2