From eaf158d02bd9fad109bed9ffe04fef19fd3e3f2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20L=C3=B3pez?= <emilio@elopez.com.ar>
Date: Mon, 25 Feb 2013 11:44:28 -0300
Subject: [PATCH] --- yaml --- r: 365287 b: refs/heads/master c:
 8eb896ab7a716308698de77073a9265f584b12fc h: refs/heads/master i:   365285:
 2578e7fef7a6a274f21181edc4e7f49b17b6c86b   365283:
 c268e62a119f90560c15771ee064cf82058baa9d   365279:
 65952d26fd8fee798f5b9b560901625134990e70 v: v3

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 trunk/Documentation/arm/sunxi/clocks.txt | 56 ++++++++++++++++++++++++
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diff --git a/trunk/Documentation/arm/sunxi/clocks.txt b/trunk/Documentation/arm/sunxi/clocks.txt
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+Frequently asked questions about the sunxi clock system
+=======================================================
+
+This document contains useful bits of information that people tend to ask
+about the sunxi clock system, as well as accompanying ASCII art when adequate.
+
+Q: Why is the main 24MHz oscillator gatable? Wouldn't that break the
+   system?
+
+A: The 24MHz oscillator allows gating to save power. Indeed, if gated
+   carelessly the system would stop functioning, but with the right
+   steps, one can gate it and keep the system running. Consider this
+   simplified suspend example:
+
+   While the system is operational, you would see something like
+
+      24MHz         32kHz
+       |
+      PLL1
+       \
+        \_ CPU Mux
+             |
+           [CPU]
+
+   When you are about to suspend, you switch the CPU Mux to the 32kHz
+   oscillator:
+
+      24Mhz         32kHz
+       |              |
+      PLL1            |
+                     /
+           CPU Mux _/
+             |
+           [CPU]
+
+    Finally you can gate the main oscillator
+
+                    32kHz
+                      |
+                      |
+                     /
+           CPU Mux _/
+             |
+           [CPU]
+
+Q: Were can I learn more about the sunxi clocks?
+
+A: The linux-sunxi wiki contains a page documenting the clock registers,
+   you can find it at
+
+        http://linux-sunxi.org/A10/CCM
+
+   The authoritative source for information at this time is the ccmu driver
+   released by Allwinner, you can find it at
+
+        https://github.com/linux-sunxi/linux-sunxi/tree/sunxi-3.0/arch/arm/mach-sun4i/clock/ccmu