drm/i915: Add more control to wait_for routines

This patch adds a little more control to a couple wait_for routines such
that we can avoid open-coding read/wait/timeout patterns which:
 - need the value of the register after the wait_for
 - run arbitrary operation for the read portion

This patch also chooses the correct sleep function (based on
timers-howto.txt) for the polling interval the caller specifies.

Changes in v2:
- Added to the series
Changes in v3:
- Rebased on drm-intel-next-queued and the new Wmin/max _wait_for
- Removed msleep option
Changes in v4:
- Removed ; for OP in _wait_for (Chris)
- Moved reg_value definition above ret (Chris)
Changes in v4:
- checkpatch whitespace fix
Changes in v5:
- None
Changes in v6:
- None

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-3-seanpaul@chromium.org

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 30f791f89d6494f3e24e344dfd3beb26d30c1a5b..9848e8eb00749341eef2ea5ffb1dd2fb22f4075b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -41,20 +41,21 @@
 #include <drm/drm_atomic.h>
 
 /**
- * _wait_for - magic (register) wait macro
+ * __wait_for - magic wait macro
  *
- * Does the right thing for modeset paths when run under kdgb or similar atomic
- * contexts. Note that it's important that we check the condition again after
- * having timed out, since the timeout could be due to preemption or similar and
- * we've never had a chance to check the condition before the timeout.
+ * Macro to help avoid open coding check/wait/timeout patterns. Note that it's
+ * important that we check the condition again after having timed out, since the
+ * timeout could be due to preemption or similar and we've never had a chance to
+ * check the condition before the timeout.
  */
-#define _wait_for(COND, US, Wmin, Wmax) ({ \
+#define __wait_for(OP, COND, US, Wmin, Wmax) ({ \
        unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1;   \
        long wait__ = (Wmin); /* recommended min for usleep is 10 us */ \
        int ret__;                                                      \
        might_sleep();                                                  \
        for (;;) {                                                      \
                bool expired__ = time_after(jiffies, timeout__);        \
+               OP;                                                     \
                if (COND) {                                             \
                        ret__ = 0;                                      \
                        break;                                          \
@@ -70,7 +71,9 @@
        ret__;                                                          \
 })
 
-#define wait_for(COND, MS)     _wait_for((COND), (MS) * 1000, 10, 1000)
+#define _wait_for(COND, US, Wmin, Wmax)        __wait_for(, (COND), (US), (Wmin), \
+                                                  (Wmax))
+#define wait_for(COND, MS)             _wait_for((COND), (MS) * 1000, 10, 1000)
 
 /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
 #if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 89547b614aa6db389d9abfb56d8703ef79d42dd9..129c8ac77985a8f8d960c09dc196eb3476d4501b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1767,12 +1767,14 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
 }
 
 /**
- * intel_wait_for_register - wait until register matches expected state
+ * __intel_wait_for_register - wait until register matches expected state
  * @dev_priv: the i915 device
  * @reg: the register to read
  * @mask: mask to apply to register value
  * @value: expected value
- * @timeout_ms: timeout in millisecond
+ * @fast_timeout_us: fast timeout in microsecond for atomic/tight wait
+ * @slow_timeout_ms: slow timeout in millisecond
+ * @out_value: optional placeholder to hold registry value
  *
  * This routine waits until the target register @reg contains the expected
  * @value after applying the @mask, i.e. it waits until ::
@@ -1783,14 +1785,17 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
  *
  * Returns 0 if the register matches the desired condition, or -ETIMEOUT.
  */
-int intel_wait_for_register(struct drm_i915_private *dev_priv,
+int __intel_wait_for_register(struct drm_i915_private *dev_priv,
                            i915_reg_t reg,
                            u32 mask,
                            u32 value,
-                           unsigned int timeout_ms)
+                           unsigned int fast_timeout_us,
+                           unsigned int slow_timeout_ms,
+                           u32 *out_value)
 {
        unsigned fw =
                intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
+       u32 reg_value;
        int ret;
 
        might_sleep();
@@ -1800,14 +1805,18 @@ int intel_wait_for_register(struct drm_i915_private *dev_priv,
 
        ret = __intel_wait_for_register_fw(dev_priv,
                                           reg, mask, value,
-                                          2, 0, NULL);
+                                          fast_timeout_us, 0, &reg_value);
 
        intel_uncore_forcewake_put__locked(dev_priv, fw);
        spin_unlock_irq(&dev_priv->uncore.lock);
 
        if (ret)
-               ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value,
-                              timeout_ms);
+               ret = __wait_for(reg_value = I915_READ_NOTRACE(reg),
+                                (reg_value & mask) == value,
+                                slow_timeout_ms * 1000, 10, 1000);
+
+       if (out_value)
+               *out_value = reg_value;
 
        return ret;
 }

diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
index 9ce079b5dd0d85d55e0aeca2b45ce54c5070bcb9..bed019ef000fa6677c22e58711e6be23d6164645 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.h
+++ b/drivers/gpu/drm/i915/intel_uncore.h
@@ -163,11 +163,23 @@ void intel_uncore_forcewake_put__locked(struct drm_i915_private *dev_priv,
 void intel_uncore_forcewake_user_get(struct drm_i915_private *dev_priv);
 void intel_uncore_forcewake_user_put(struct drm_i915_private *dev_priv);
 
+int __intel_wait_for_register(struct drm_i915_private *dev_priv,
+                             i915_reg_t reg,
+                             u32 mask,
+                             u32 value,
+                             unsigned int fast_timeout_us,
+                             unsigned int slow_timeout_ms,
+                             u32 *out_value);
+static inline
 int intel_wait_for_register(struct drm_i915_private *dev_priv,
                            i915_reg_t reg,
                            u32 mask,
                            u32 value,
-                           unsigned int timeout_ms);
+                           unsigned int timeout_ms)
+{
+       return __intel_wait_for_register(dev_priv, reg, mask, value, 2,
+                                        timeout_ms, NULL);
+}
 int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
                                 i915_reg_t reg,
                                 u32 mask,