In order to ensure that our system suspend and resume callbacks are
called in the correct order wrt. those of the HDA driver add a device
link to the HDA driver during audio component binding time. With i915 as
the supplier and HDA as the consumer the PM framework will guarantee
the HDA->i915 suspend (and shutdown) and i915->HDA resume order.
Atm, the lack of this ordering is not a problem, since all the i915
suspend/resume steps that need to be ordered wrt. the HDA driver's
suspend/resume steps are separated out to the i915
suspend_late/resume_early hooks. That will change in a follow-up
patchset where we'll need this ordering guarantee for steps that are in
the i915 suspend/resume hooks (and which can't be moved to
suspend_late/resume_early for other reasons). So this patch is a
preparation for that follow-up patchset.
The change also allows us to move towards removing the i915
suspend_late/resume_early hooks alltogether.
Since we only need to ensure the ordering during suspend/resume and not
during driver probing create the link with DL_FLAG_STATELESS. Since the
probe time ordering has to be optional we use the component framework
for that.
Similarly for runtime PM we depend on the audio driver getting/putting
an i915 runtime PM reference whenever it needs it (along with the proper
i915 display power domain) via the audio component ops get_power /
put_power hooks. So we create the device link without
DL_FLAG_PM_RUNTIME.
v2: (Ville)
- Add a note to the commit message about not using the device link
runtime PM ordering.
- Handle the error return from device_link_add().
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Cc: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_audio.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index 769f3f586661..b2c656a46be6 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -912,6 +912,9 @@ static int i915_audio_component_bind(struct device *i915_kdev,
if (WARN_ON(acomp->base.ops || acomp->base.dev))
return -EEXIST;
+ if (WARN_ON(!device_link_add(hda_kdev, i915_kdev, DL_FLAG_STATELESS)))
+ return -ENOMEM;
+
drm_modeset_lock_all(&dev_priv->drm);
acomp->base.ops = &i915_audio_component_ops;
acomp->base.dev = i915_kdev;
@@ -935,6 +938,8 @@ static void i915_audio_component_unbind(struct device *i915_kdev,
acomp->base.dev = NULL;
dev_priv->audio_component = NULL;
drm_modeset_unlock_all(&dev_priv->drm);
+
+ device_link_remove(hda_kdev, i915_kdev);
}
static const struct component_ops i915_audio_component_bind_ops = {
--
2.13.2
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