Re: [Intel-gfx] [PATCH] drm/i915: fix plane/cursor handling when runtime suspended

Paulo Zanoni
2014-08-12T19:12:38Z

2014-08-12 16:09 GMT-03:00 Chris Wilson <chris@chris-wilson.co.uk>:
> On Tue, Aug 12, 2014 at 03:55:12PM -0300, Paulo Zanoni wrote:
>> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>>
>> If we're runtime suspended and try to use the plane interfaces, we
>> will get a lot of WARNs saying we did the wrong thing.
>>
>> We need to get runtime PM references to pin/unpin the objects, and to
>> change the fences. The pin/unpin functions are the ideal places for
>> this, but intel_crtc_cursor_set_obj() doesn't call them, so we also
>> have to add get/put calls inside it. There is no problem if we runtime
>> suspend right after these functions are finished, because the
>> registers written are forwarded to system memory.
>>
>> Note: for a complete fix of the cursor-dpms test case, we also need
>> the patch named "drm/i915: Don't try to enable cursor from setplane
>> when crtc is disabled".
>>
>> v2: - Narrow the put/get calls on intel_crtc_cursor_set_obj() (Daniel)
>> v3: - Make get/put also surround the fence and unpin calls (Daniel and
>> Ville).
>> - Merge all the plane changes into a single patch since they're
>> the same fix.
>> - Add the comment requested by Daniel.
>> v4: - Remove spurious whitespace (Ville).
>> v5: - Remove intel_crtc_update_cursor() chunk since Ville did an
>> equivalent fix in another patch (Ville).
>>
>> Testcase: igt/pm_rpm/cursor
>> Testcase: igt/pm_rpm/cursor-dpms
>> Testcase: igt/pm_rpm/legacy-planes
>> Testcase: igt/pm_rpm/legacy-planes-dpms
>> Testcase: igt/pm_rpm/universal-planes
>> Testcase: igt/pm_rpm/universal-planes-dpms
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81645
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_display.c | 35 ++++++++++++++++++++++++++++++++++-
>> 1 file changed, 34 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index a1cf052..2db9e06 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -2149,6 +2149,15 @@ intel_pin_and_fence_fb_obj(struct drm_device *dev,
>> if (need_vtd_wa(dev) && alignment < 256 * 1024)
>> alignment = 256 * 1024;
>>
>> + /*
>> + * Global gtt pte registers are special registers which actually forward
>> + * writes to a chunk of system memory. Which means that there is no risk
>> + * that the register values disappear as soon as we call
>> + * intel_runtime_pm_put(), so it is correct to wrap only the
>> + * pin/unpin/fence and not more.
>> + */
>> + intel_runtime_pm_get(dev_priv);
>> +
>> dev_priv->mm.interruptible = false;
>> ret = i915_gem_object_pin_to_display_plane(obj, alignment, pipelined);
>> if (ret)
>> @@ -2166,21 +2175,30 @@ intel_pin_and_fence_fb_obj(struct drm_device *dev,
>> i915_gem_object_pin_fence(obj);
>>
>> dev_priv->mm.interruptible = true;
>> + intel_runtime_pm_put(dev_priv);
>> return 0;
>>
>> err_unpin:
>> i915_gem_object_unpin_from_display_plane(obj);
>> err_interruptible:
>> dev_priv->mm.interruptible = true;
>> + intel_runtime_pm_put(dev_priv);
>> return ret;
>> }
>>
>> void intel_unpin_fb_obj(struct drm_i915_gem_object *obj)
>> {
>> - WARN_ON(!mutex_is_locked(&obj->base.dev->struct_mutex));
>> + struct drm_device *dev = obj->base.dev;
>> + struct drm_i915_private *dev_priv = dev->dev_private;
>> +
>> + WARN_ON(!mutex_is_locked(&dev->struct_mutex));
>> +
>> + intel_runtime_pm_get(dev_priv);
>>
>> i915_gem_object_unpin_fence(obj);
>> i915_gem_object_unpin_from_display_plane(obj);
>> +
>> + intel_runtime_pm_put(dev_priv);
>> }
>
> framebuffer objects are pinned for a very long time, and the fbcon is
> permanently pinned. This should have the effect of disabling rpm
> entirely.

But we just get/put RPM around this function, not for the whole time
while the object is pinned.

> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre

--
Paulo Zanoni