author | Graeme Price <GRAEME.PRICE@NOKIA.COM> |
Fri, 15 Oct 2010 14:32:18 +0100 | |
changeset 15 | 307f4279f433 |
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307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<?xml version="1.0" encoding="utf-8"?> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<!-- This component and the accompanying materials are made available under the terms of the License |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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"Eclipse Public License v1.0" which accompanies this distribution, |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<!-- Initial Contributors: |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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Nokia Corporation - initial contribution. |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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Contributors: |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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--> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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|
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<!DOCTYPE concept |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
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PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
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<concept id="GUID-6CE68645-D8C5-52E1-88B3-76AEFB80DE51" xml:lang="en"><title>Peripherals |
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Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
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As Power Resources</title><shortdesc>Peripherals that provide services to other peripherals can be considered |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
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as power resources from the point of view of the client driver.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<p>As they can offer a service to more than one other peripheral, we suggest |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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that the driver that manages them presents a <xref href="GUID-10105403-AF16-3908-AE9E-96CF2A03AD3A.dita"><apiname>MPowerInput</apiname></xref> derived |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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interface to client peripheral drivers, providing <codeph>Use()</codeph> and <codeph>Release()</codeph> functions |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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that can be used by dependent peripheral drivers to issue power requests. |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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The driver for the peripheral providing that interface may then use the built-in |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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usage counting feature to control the peripheral power state. </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<p>A typical example of a shared Peripheral is an Inter-Component serial Bus |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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(I2C, SPI, etc): </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<codeblock id="GUID-2E454D22-496D-5D9C-9F67-281D6F340459" xml:space="preserve">class MySharedPeripheral : public MPowerInput , (other parent classes) |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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{ |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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public: |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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// from MPowerInput |
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Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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void Use(); |
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Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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void Release(); |
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Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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TUint GetCount(); |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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... |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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(other methods and data members required to model the interface) |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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}; |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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</codeblock> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<p>Special care must be taken to not create circular dependencies, for example, |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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Peripheral A depends on Peripheral B, which depends on Peripheral C which |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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depends on Peripheral A. Such circular dependencies would cause the <xref href="GUID-10105403-AF16-3908-AE9E-96CF2A03AD3A.dita#GUID-10105403-AF16-3908-AE9E-96CF2A03AD3A/GUID-606ECD77-A5F7-3408-9B63-C68C0A7B73C6"><apiname>MPowerInput::Release()</apiname></xref> mechanism |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
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not to work properly, and preventing the chain of peripherals from powering |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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down when due. </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
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<p>The shared peripheral driver’s power handler asynchronous <codeph>PowerDown()</codeph> must |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
changeset
|
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examine the usage count of that peripheral if the power manager issues a <codeph>PowerDown()</codeph> request |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
41 |
to the shared peripheral driver’s power handler while the peripheral is still |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
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in use by another driver. In this situation, the shared peripheral driver |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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must defer powering down until all the dependent peripherals have released |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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their request on it. </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
45 |
<p>Some peripherals may also be represented as power resources to prevent |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
changeset
|
46 |
the base port power saving operations inhibiting their usage. For example, |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff
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|
47 |
a base port may consider DRAM to be a shared power resource with the DMA controller, |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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or the DSP controller as clients. This will allow them to still be able to |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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access DRAM whilst the CPU is idling, thus stopping the DRAM going into self-refresh |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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if either one of its clients has pending operations on it. </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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<p>As another example, to save power some base ports might decide to reduce |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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the refresh rate of the LCD whilst the CPU is idling or even power it down |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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for short periods and rely on the persistence of the LCD to prevent degredation |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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of the user experience. However, on a multiple core solution the LCD might |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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be used by the second core (e.g. DSP), for example, for playing back video |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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whilst the main CPU is idling. In this situation the LCD should be represented |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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as a shared power resource and the DSP must be able to request usage of this |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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resource. The DSP controller software could assert a request on the LCD preventing |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
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the main CPU from initiating the power saving measures. </p> |
307f4279f433
Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
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</conbody></concept> |