Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq

[linux-2.6] / Documentation / arm / Samsung-S3C24XX / Suspend.txt

diff --git a/Documentation/arm/Samsung-S3C24XX/Suspend.txt b/Documentation/arm/Samsung-S3C24XX/Suspend.txt
index e12bc3284a272eae2c23999c30db92fdc47bfa5a..0dab6e32c130a2fc61192fd99cf95a963648beea 100644 (file)
--- a/Documentation/arm/Samsung-S3C24XX/Suspend.txt
+++ b/Documentation/arm/Samsung-S3C24XX/Suspend.txt
@@ -5,10 +5,10 @@
 Introduction
 ------------
 
-  The S3C2410 supports a low-power suspend mode, where the SDRAM is kept
+  The S3C24XX supports a low-power suspend mode, where the SDRAM is kept
   in Self-Refresh mode, and all but the essential peripheral blocks are
   powered down. For more information on how this works, please look
-  at the S3C2410 datasheets from Samsung.
+  at the relevant CPU datasheet from Samsung.
 
 
 Requirements
@@ -56,6 +56,27 @@ Machine Support
   Note, the original method of adding an late_initcall() is wrong,
   and will end up initialising all compiled machines' pm init!
 
+  The following is an example of code used for testing wakeup from
+  an falling edge on IRQ_EINT0:
+
+
+static irqreturn_t button_irq(int irq, void *pw)
+{
+       return IRQ_HANDLED;
+}
+
+statuc void __init machine_init(void)
+{
+       ...
+
+       request_irq(IRQ_EINT0, button_irq, IRQF_TRIGGER_FALLING,
+                  "button-irq-eint0", NULL);
+
+       enable_irq_wake(IRQ_EINT0);
+
+       s3c2410_pm_init();
+}
+
 
 Debugging
 ---------
@@ -70,6 +91,12 @@ Debugging
      care should be taken that any external clock sources that the UARTs
      rely on are still enabled at that point.
 
+  3) If any debugging is placed in the resume path, then it must have the
+     relevant clocks and peripherals setup before use (ie, bootloader).
+
+     For example, if you transmit a character from the UART, the baud
+     rate and uart controls must be setup beforehand.
+
 
 Configuration
 -------------
@@ -89,6 +116,10 @@ Configuration
     Allows the entire memory to be checksummed before and after the
     suspend to see if there has been any corruption of the contents.
 
+    Note, the time to calculate the CRC is dependant on the CPU speed
+    and the size of memory. For an 64Mbyte RAM area on an 200MHz
+    S3C2410, this can take approximately 4 seconds to complete.
+
     This support requires the CRC32 function to be enabled.