drm/i915: Track the number of times we have woken the GPU up

By counting the number of times we have woken up, we have a very simple
means of defining an epoch, which will come in handy if we want to
perform deferred tasks at the end of an epoch (i.e. while we are going
to sleep) without imposing on the next activity cycle.

v2: No reason to specify precise number of bits here.
v3: Take Tvrtko's advice and reserve 0 as an invalid epoch.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180124113608.14909-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 80dc679c0f0169098b096c164dba2333584b7069..338735252e23d0576d709a6fe39e6bcbf3366b60 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2717,7 +2717,8 @@ static int i915_runtime_pm_status(struct seq_file *m, void *unused)
        if (!HAS_RUNTIME_PM(dev_priv))
                seq_puts(m, "Runtime power management not supported\n");
 
-       seq_printf(m, "GPU idle: %s\n", yesno(!dev_priv->gt.awake));
+       seq_printf(m, "GPU idle: %s (epoch %u)\n",
+                  yesno(!dev_priv->gt.awake), dev_priv->gt.epoch);
        seq_printf(m, "IRQs disabled: %s\n",
                   yesno(!intel_irqs_enabled(dev_priv)));
 #ifdef CONFIG_PM
@@ -3150,8 +3151,8 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 
        intel_runtime_pm_get(dev_priv);
 
-       seq_printf(m, "GT awake? %s\n",
-                  yesno(dev_priv->gt.awake));
+       seq_printf(m, "GT awake? %s (epoch %u)\n",
+                  yesno(dev_priv->gt.awake), dev_priv->gt.epoch);
        seq_printf(m, "Global active requests: %d\n",
                   dev_priv->gt.active_requests);
        seq_printf(m, "CS timestamp frequency: %u kHz\n",

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c707eee2102b9151117a2fd0f1466d40476a9627..1f9df2861d54304ca1e9dd8aa6e654064583e328 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2312,6 +2312,12 @@ struct drm_i915_private {
                 */
                bool awake;
 
+               /**
+                * The number of times we have woken up.
+                */
+               unsigned int epoch;
+#define I915_EPOCH_INVALID 0
+
                /**
                 * We leave the user IRQ off as much as possible,
                 * but this means that requests will finish and never

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index a0f451b4a4e8d706d58ed896734102e522af7008..06ec27a68f5cf894b04751adbd0d2728cc4a1ef0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -274,6 +274,8 @@ static void mark_busy(struct drm_i915_private *i915)
        intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ);
 
        i915->gt.awake = true;
+       if (unlikely(++i915->gt.epoch == 0)) /* keep 0 as invalid */
+               i915->gt.epoch = 1;
 
        intel_enable_gt_powersave(i915);
        i915_update_gfx_val(i915);