drm/i915: Generalise common GPU engine reset request/unrequest code

GPU engine reset handshaking is something that is applicable to both full GPU
reset and engine reset, which is something that is part of the upcoming TDR
per-engine hang recovery patches. Break out the common engine reset
request/unrequest code (originally written by Mika Kuoppala) for reuse later
in the TDR enablement patch series.

v2: correct indentation and drop unused returned value (Mika)
v3: We have forcewake during reset so use *_FW reg access (Mika)

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Tomas Elf <tomas.elf@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
[Mika: Fixed format warning]
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456929984-16323-1-git-send-email-mika.kuoppala@intel.com

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 436d8f2..d31447f 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1531,13 +1531,40 @@ static int gen6_do_reset(struct drm_device *dev)
        return ret;
 }
 
-static int wait_for_register(struct drm_i915_private *dev_priv,
-                            i915_reg_t reg,
-                            const u32 mask,
-                            const u32 value,
-                            const unsigned long timeout_ms)
+static int wait_for_register_fw(struct drm_i915_private *dev_priv,
+                               i915_reg_t reg,
+                               const u32 mask,
+                               const u32 value,
+                               const unsigned long timeout_ms)
 {
-       return wait_for((I915_READ(reg) & mask) == value, timeout_ms);
+       return wait_for((I915_READ_FW(reg) & mask) == value, timeout_ms);
+}
+
+static int gen8_request_engine_reset(struct intel_engine_cs *engine)
+{
+       int ret;
+       struct drm_i915_private *dev_priv = engine->dev->dev_private;
+
+       I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
+                     _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
+
+       ret = wait_for_register_fw(dev_priv,
+                                  RING_RESET_CTL(engine->mmio_base),
+                                  RESET_CTL_READY_TO_RESET,
+                                  RESET_CTL_READY_TO_RESET,
+                                  700);
+       if (ret)
+               DRM_ERROR("%s: reset request timeout\n", engine->name);
+
+       return ret;
+}
+
+static void gen8_unrequest_engine_reset(struct intel_engine_cs *engine)
+{
+       struct drm_i915_private *dev_priv = engine->dev->dev_private;
+
+       I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
+                     _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
 }
 
 static int gen8_do_reset(struct drm_device *dev)
@@ -1546,26 +1573,15 @@ static int gen8_do_reset(struct drm_device *dev)
        struct intel_engine_cs *engine;
        int i;
 
-       for_each_ring(engine, dev_priv, i) {
-               I915_WRITE(RING_RESET_CTL(engine->mmio_base),
-                          _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
-
-               if (wait_for_register(dev_priv,
-                                     RING_RESET_CTL(engine->mmio_base),
-                                     RESET_CTL_READY_TO_RESET,
-                                     RESET_CTL_READY_TO_RESET,
-                                     700)) {
-                       DRM_ERROR("%s: reset request timeout\n", engine->name);
+       for_each_ring(engine, dev_priv, i)
+               if (gen8_request_engine_reset(engine))
                        goto not_ready;
-               }
-       }
 
        return gen6_do_reset(dev);
 
 not_ready:
        for_each_ring(engine, dev_priv, i)
-               I915_WRITE(RING_RESET_CTL(engine->mmio_base),
-                          _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
+               gen8_unrequest_engine_reset(engine);
 
        return -EIO;
 }