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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2013-05-21 09:52:16 +0200 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2013-05-21 09:52:16 +0200 |
commit | e1b73cba13a0cc68dd4f746eced15bd6bb24cda4 (patch) | |
tree | b1c9e10730724024a700031ad56c20419dabb500 /Documentation/arm/sunxi/clocks.txt | |
parent | 98304ad186296dc1e655399e28d5973c21db6a73 (diff) | |
parent | c7788792a5e7b0d5d7f96d0766b4cb6112d47d75 (diff) | |
download | blackbird-op-linux-e1b73cba13a0cc68dd4f746eced15bd6bb24cda4.tar.gz blackbird-op-linux-e1b73cba13a0cc68dd4f746eced15bd6bb24cda4.zip |
Merge tag 'v3.10-rc2' into drm-intel-next-queued
Backmerge Linux 3.10-rc2 since the various (rather trivial) conflicts
grew a bit out of hand. intel_dp.c has the only real functional
conflict since the logic changed while dev_priv->edp.bpp was moved
around.
Also squash in a whitespace fixup from Ben Widawsky for
i915_gem_gtt.c, git seems to do something pretty strange in there
(which I don't fully understand tbh).
Conflicts:
drivers/gpu/drm/i915/i915_reg.h
drivers/gpu/drm/i915/intel_dp.c
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'Documentation/arm/sunxi/clocks.txt')
-rw-r--r-- | Documentation/arm/sunxi/clocks.txt | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/Documentation/arm/sunxi/clocks.txt b/Documentation/arm/sunxi/clocks.txt new file mode 100644 index 000000000000..e09a88aa3136 --- /dev/null +++ b/Documentation/arm/sunxi/clocks.txt @@ -0,0 +1,56 @@ +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 |