LineageOS/android_hardware_libhardware
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

camera2: Update HAL docs on eviction behavior.

Browse Source 
Bug: 19186859
Change-Id: Ie051f966a758c68d354250c245a87df57a4f4ae3
This commit is contained in:
Ruben Brunk
2015-03-10 11:53:12 -07:00
parent ce295acf75
commit 1fa09029a9
1 changed files with 115 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

125
include/hardware/camera_common.h
View File

@@ -236,10 +236,12 @@ typedef struct camera_info {
const camera_metadata_t *static_camera_characteristics;
/**
* The total resource "cost" of using this this camera, represented as
* an integer value in the range [0, 100] where 100 represents total usage
* of the shared resource that is the limiting bottleneck of the camera
* subsystem.
* The total resource "cost" of using this camera, represented as an integer
* value in the range [0, 100] where 100 represents total usage of the shared
* resource that is the limiting bottleneck of the camera subsystem. This may
* be a very rough estimate, and is used as a hint to the camera service to
* determine when to disallow multiple applications from simultaneously
* opening different cameras advertised by the camera service.
*
* The camera service must be able to simultaneously open and use any
* combination of camera devices exposed by the HAL where the sum of
@@ -249,12 +251,112 @@ typedef struct camera_info {
* available in the configuration settings exposed for that device through
* the camera metadata.
*
* Note: The camera service may still attempt to simultaneously open
* combinations of camera devices with a total resource cost > 100. This
* may succeed or fail. If this succeeds, combinations of configurations
* that are not supported should fail during the configure calls. If the
* total resource cost is <= 100, configuration should never fail due to
* resource constraints.
* The camera service may still attempt to simultaneously open combinations
* of camera devices with a total resource cost > 100. This may succeed or
* fail. If this succeeds, combinations of configurations that are not
* supported due to resource constraints from having multiple open devices
* should fail during the configure calls. If the total resource cost is
* <= 100, open and configure should never fail for any stream configuration
* settings or other device capabilities that would normally succeed for a
* device when it is the only open camera device.
*
* This field will be used to determine whether background applications are
* allowed to use this camera device while other applications are using other
* camera devices. Note: multiple applications will never be allowed by the
* camera service to simultaneously open the same camera device.
*
* Example use cases:
*
* Ex. 1: Camera Device 0 = Back Camera
* Camera Device 1 = Front Camera
* - Using both camera devices causes a large framerate slowdown due to
* limited ISP bandwidth.
*
* Configuration:
*
* Camera Device 0 - resource_cost = 51
* conflicting_devices = null
* Camera Device 1 - resource_cost = 51
* conflicting_devices = null
*
* Result:
*
* Since the sum of the resource costs is > 100, if a higher-priority
* application has either device open, no lower-priority applications will be
* allowed by the camera service to open either device. If a lower-priority
* application is using a device that a higher-priority subsequently attempts
* to open, the lower-priority application will be forced to disconnect the
* the device.
*
* If the highest-priority application chooses, it may still attempt to open
* both devices (since these devices are not listed as conflicting in the
* conflicting_devices fields), but usage of these devices may fail in the
* open or configure calls.
*
* Ex. 2: Camera Device 0 = Left Back Camera
* Camera Device 1 = Right Back Camera
* Camera Device 2 = Combined stereo camera using both right and left
* back camera sensors used by devices 0, and 1
* Camera Device 3 = Front Camera
* - Due to do hardware constraints, up to two cameras may be open at once. The
* combined stereo camera may never be used at the same time as either of the
* two back camera devices (device 0, 1), and typically requires too much
* bandwidth to use at the same time as the front camera (device 3).
*
* Configuration:
*
* Camera Device 0 - resource_cost = 50
* conflicting_devices = { 2 }
* Camera Device 1 - resource_cost = 50
* conflicting_devices = { 2 }
* Camera Device 2 - resource_cost = 100
* conflicting_devices = { 0, 1 }
* Camera Device 3 - resource_cost = 50
* conflicting_devices = null
*
* Result:
*
* Based on the conflicting_devices fields, the camera service guarantees that
* the following sets of open devices will never be allowed: { 1, 2 }, { 0, 2 }.
*
* Based on the resource_cost fields, if a high-priority foreground application
* is using camera device 0, a background application would be allowed to open
* camera device 1 or 3 (but would be forced to disconnect it again if the
* foreground application opened another device).
*
* The highest priority application may still attempt to simultaneously open
* devices 0, 2, and 3, but the HAL may fail in open or configure calls for
* this combination.
*
* Ex. 3: Camera Device 0 = Back Camera
* Camera Device 1 = Front Camera
* Camera Device 2 = Low-power Front Camera that uses the same
* sensor as device 1, but only exposes image stream
* resolutions that can be used in low-power mode
* - Using both front cameras (device 1, 2) at the same time is impossible due
* a shared physical sensor. Using the back and "high-power" front camera
* (device 1) may be impossible for some stream configurations due to hardware
* limitations, but the "low-power" front camera option may always be used as
* it has special dedicated hardware.
*
* Configuration:
*
* Camera Device 0 - resource_cost = 100
* conflicting_devices = null
* Camera Device 1 - resource_cost = 100
* conflicting_devices = { 2 }
* Camera Device 2 - resource_cost = 0
* conflicting_devices = { 1 }
* Result:
*
* Based on the conflicting_devices fields, the camera service guarantees that
* the following sets of open devices will never be allowed: { 1, 2 }.
*
* Based on the resource_cost fields, only the highest priority application
* may attempt to open both device 0 and 1 at the same time. If a higher-priority
* application is not using device 1 or 2, a low-priority background application
* may open device 2 (but will be forced to disconnect it if a higher-priority
* application subsequently opens device 1 or 2).
*
* Version information (based on camera_module_t.common.module_api_version):
*
@@ -281,6 +383,9 @@ typedef struct camera_info {
* The camera service will never simultaneously open any of the devices
* in this list while this camera device is open.
*
* The strings pointed to in this field will not be cleaned up by the camera
* service, and must remain while this device is plugged in.
*
* Version information (based on camera_module_t.common.module_api_version):
*
* CAMERA_MODULE_API_VERSION_2_3 or lower: