On 7/30/19 1:14 AM, Chris Wilson wrote:
Quoting Daniele Ceraolo Spurio (2019-07-29 23:28:00)
When coming out of S3/S4 we sanitize and re-init the HW, which includes
enabling communication during uc_init_hw. We therefore don't want to do
that again in uc_resume and can just tell GuC to reload its state.

Signed-off-by: Daniele Ceraolo Spurio <[email protected]>
Cc: Michal Wajdeczko <[email protected]>
Cc: Chris Wilson <[email protected]>
---
  drivers/gpu/drm/i915/gt/uc/intel_uc.c | 16 +++++++++++++++-
  1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c 
b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index fafa9be1e12a..34706a753793 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -233,11 +233,18 @@ static void guc_disable_interrupts(struct intel_guc *guc)
         guc->interrupts.disable(guc);
  }
+static bool guc_communication_enabled(struct intel_guc *guc)
+{
+       return guc->send != intel_guc_send_nop;
+}
+
  static int guc_enable_communication(struct intel_guc *guc)
  {
         struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
         int ret;
+ GEM_BUG_ON(guc_communication_enabled(guc));
+
         ret = intel_guc_ct_enable(&guc->ct);
         if (ret)
                 return ret;
@@ -558,7 +565,14 @@ int intel_uc_resume(struct intel_uc *uc)
         if (!intel_guc_is_running(guc))
                 return 0;
- guc_enable_communication(guc);
+       /*
+        * When coming out of S3/S4 we sanitize and re-init the HW, so
+        * communication is already re-enabled at this point and we just need
+        * to tell GuC to reload its internal state. During runtime resume we
+        * instead want to re-init everything.
+        */
+       if (!guc_communication_enabled(guc))
+               guc_enable_communication(guc);

We distinguish runtime_suspend from suspend, but not runtime_resume from
resume. Is that distinction worthwhile, could we use it be more strict
over the expected state?
-Chris


The actual actions we want to perform in both cases are the same, apart from the communication side. What about:

static int __uc_resume(struct intel_uc *uc, bool enable_comm)
{
        if (!intel_guc_is_running())
                return 0;

        GEM_BUG_ON(enable comm == guc_communication_enabled());

        if (enable_comm)
                guc_enable_communication();

        err = intel_guc_resume();
}

intel_uc_runtime_resume()
{
        __uc_resume(uc, true);
}

intel_uc_resume()
{
        __uc_resume(uc, false);
}

Daniele
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