Document reentrancy and error conditions
The hotplug callback is non-reentrant. The display config functions
return an error if called for a disconnected display type.
Change-Id: I52d11a53f9b30a7c39e98b0a9b07eb97a3d2becd
diff --git a/include/hardware/hwcomposer.h b/include/hardware/hwcomposer.h
index 0bebb98..f03ac70 100644
--- a/include/hardware/hwcomposer.h
+++ b/include/hardware/hwcomposer.h
@@ -326,6 +326,9 @@
* other threads may be calling into the h/w composer while the callback
* is in progress.
*
+ * The h/w composer must serialize calls to the hotplug callback; only
+ * one thread may call it at a time.
+ *
* This callback will be NULL if the h/w composer is using
* HWC_DEVICE_API_VERSION_1_0.
*/
@@ -485,7 +488,8 @@
* implementation should choose one and report it as the first config in
* the list. Reporting the not-chosen configs is not required.
*
- * Returns 0 on success or -errno on error.
+ * Returns 0 on success or -errno on error. If disp is a hotpluggable
+ * display type and no display is connected, an error should be returned.
*
* This field is REQUIRED for HWC_DEVICE_API_VERSION_1_1 and later.
* It should be NULL for previous versions.
@@ -506,8 +510,12 @@
*
* This field is REQUIRED for HWC_DEVICE_API_VERSION_1_1 and later.
* It should be NULL for previous versions.
+ *
+ * If disp is a hotpluggable display type and no display is connected,
+ * or if config is not a valid configuration for the display, a negative
+ * value should be returned.
*/
- void (*getDisplayAttributes)(struct hwc_composer_device_1* dev, int disp,
+ int (*getDisplayAttributes)(struct hwc_composer_device_1* dev, int disp,
uint32_t config, const uint32_t* attributes, int32_t* values);
/*