From eb80d6ce667e707e5a1ee7444203aa03fdb6b2e0 Mon Sep 17 00:00:00 2001
From: Norman Feske <norman.feske@genode-labs.com>
Date: Thu, 7 Oct 2021 10:33:11 +0200
Subject: [PATCH] usb_webcam: on/off dependent on capture client

This commit removes the report service from the usb_webcam pkg, which
was used to enable or disable the webcam driver. The on/off state is
instead controlled by the presence of a capture client. That is, once a
capture client appears, the webcam driver is started. Vice versa, once
no capture client exists, the webcam driver is removed automatically.

Internally, the detection of presence of a capture client is based on
nitpicker's 'displays' report, which is consumed as input of the
rom_filter, which in turn generates the configuration of a dynamic sub
init.

Fixes #4287
---
 repos/libports/recipes/pkg/usb_webcam/runtime |  2 +-
 .../recipes/raw/usb_webcam/usb_webcam.config  | 26 ++++++++++---------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/repos/libports/recipes/pkg/usb_webcam/runtime b/repos/libports/recipes/pkg/usb_webcam/runtime
index cbb2476ae9..ea7354a3f7 100644
--- a/repos/libports/recipes/pkg/usb_webcam/runtime
+++ b/repos/libports/recipes/pkg/usb_webcam/runtime
@@ -1,5 +1,5 @@
 <runtime binary="init" caps="800" ram="64M" config="usb_webcam.config">
-	<provides> <capture /> <report /> </provides>
+	<provides> <capture /> </provides>
 	<requires> <timer /> <usb /> <rm /> </requires>
 	<content>
 		<rom label="ld.lib.so"/>
diff --git a/repos/libports/recipes/raw/usb_webcam/usb_webcam.config b/repos/libports/recipes/raw/usb_webcam/usb_webcam.config
index cc137ba03d..a017619f88 100644
--- a/repos/libports/recipes/raw/usb_webcam/usb_webcam.config
+++ b/repos/libports/recipes/raw/usb_webcam/usb_webcam.config
@@ -12,7 +12,6 @@
 
 	<default caps="100"/>
 
-	<service name="Report"> <default-policy> <child name="report_rom" label="capture"/> </default-policy> </service>
 	<service name="Capture"> <default-policy> <child name="nitpicker_camera"/> </default-policy> </service>
 
 	<start name="nitpicker_camera" caps="150">
@@ -22,11 +21,13 @@
 			<service name="Gui"/> <service name="Capture"/>
 		</provides>
 		<config request_framebuffer="no">
+			<report displays="yes"/>
 			<capture/>
 			<domain name="" layer="1" content="client" label="no" />
 			<default-policy domain=""/>
 		</config>
 		<route>
+			<service name="Report"> <child name="report_rom"/> </service>
 			<any-service> <parent/> </any-service>
 		</route>
 	</start>
@@ -36,25 +37,28 @@
 		<resource name="RAM" quantum="2M"/>
 		<provides> <service name="Report"/> <service name="ROM"/> </provides>
 		<config verbose="no">
-			<policy label="capture" report="capture"/>
+			<policy label="webcam_config -> displays" report="nitpicker_camera -> displays"/>
 		</config>
 		<route>
 			<any-service> <parent /> </any-service>
 		</route>
 	</start>
 
-	<start name="webcam-config">
+	<start name="webcam_config">
 		<binary name="rom_filter"/>
 		<resource name="RAM" quantum="1M"/>
 		<provides> <service name="ROM"/> </provides>
 		<config verbose="no">
-			<input name="webcam_enabled" rom="capture" node="capture">
-				<attribute name="enabled"/>
+			<input name="capture_width" rom="displays" node="displays" default="">
+				<node type="display">
+					<attribute name="width"/>
+				</node>
 			</input>
 
 			<output node="config">
-				<if> <has_value input="webcam_enabled" value="true"/>
-				<then>
+				<if> <has_value input="capture_width" value=""/>
+				<then> </then>
+				<else>
 					<inline>
 						<parent-provides>
 							<service name="ROM"/>
@@ -82,13 +86,11 @@
 							</route>
 						</start>
 					</inline>
-				</then></if>
+				</else></if>
 			</output>
 		</config>
 		<route>
-			<service name="ROM" label="capture">
-				<child name="report_rom" label="capture"/>
-			</service>
+			<service name="ROM" label="displays"> <child name="report_rom"/> </service>
 			<any-service> <parent/> </any-service>
 		</route>
 	</start>
@@ -98,7 +100,7 @@
 		<resource name="RAM" quantum="50MB"/>
 		<route>
 			<service name="ROM" label="config">
-				<child name="webcam-config" label="config"/>
+				<child name="webcam_config" label="config"/>
 			</service>
 			<service name="Gui"> <child name="nitpicker_camera"/> </service>
 			<any-service> <parent/> </any-service>