Magellan Linux

  • Back to homepage
    • /[alx-svn]/alx-src/trunk/kernel26-alx/linux/Documentation/arm/Samsung-S3C24XX/Suspend.txt

    Contents of /alx-src/trunk/kernel26-alx/linux/Documentation/arm/Samsung-S3C24XX/Suspend.txt

    Parent Directory Parent Directory | Revision Log Revision Log

    Revision 628 - (show annotations) (download)
    Wed Mar 4 10:48:58 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 3156 byte(s) 
    import linux sources based on 2.6.12-alx-r9:
 -using linux-2.6.12.6
 -using 2.6.12-ck6 patch set
 -using fbsplash-0.9.2-r3
 -using vesafb-tng-0.9-rc7
 -using squashfs-2.2
 -added cddvd-cmdfilter-drop.patch as ck dropped it
 -added via-epia-dri (cle266) patch
 -added zd1211-svn-32 wlan driver (http://zd1211.ath.cx/download/)
 -added debian patches to zd1211 for wep256 etc
    1 S3C24XX Suspend Support
    2 =======================
    3
    4
    5 Introduction
    6 ------------
    7
    8 The S3C2410 supports a low-power suspend mode, where the SDRAM is kept
    9 in Self-Refresh mode, and all but the essential peripheral blocks are
    10 powered down. For more information on how this works, please look
    11 at the S3C2410 datasheets from Samsung.
    12
    13
    14 Requirements
    15 ------------
    16
    17 1) A bootloader that can support the necessary resume operation
    18
    19 2) Support for at least 1 source for resume
    20
    21 3) CONFIG_PM enabled in the kernel
    22
    23 4) Any peripherals that are going to be powered down at the same
    24 time require suspend/resume support.
    25
    26
    27 Resuming
    28 --------
    29
    30 The S3C2410 user manual defines the process of sending the CPU to
    31 sleep and how it resumes. The default behaviour of the Linux code
    32 is to set the GSTATUS3 register to the physical address of the
    33 code to resume Linux operation.
    34
    35 GSTATUS4 is currently left alone by the sleep code, and is free to
    36 use for any other purposes (for example, the EB2410ITX uses this to
    37 save memory configuration in).
    38
    39
    40 Machine Support
    41 ---------------
    42
    43 The machine specific functions must call the s3c2410_pm_init() function
    44 to say that its bootloader is capable of resuming. This can be as
    45 simple as adding the following to the machine's definition:
    46
    47 INITMACHINE(s3c2410_pm_init)
    48
    49 A board can do its own setup before calling s3c2410_pm_init, if it
    50 needs to setup anything else for power management support.
    51
    52 There is currently no support for over-riding the default method of
    53 saving the resume address, if your board requires it, then contact
    54 the maintainer and discuss what is required.
    55
    56 Note, the original method of adding an late_initcall() is wrong,
    57 and will end up initialising all compiled machines' pm init!
    58
    59
    60 Debugging
    61 ---------
    62
    63 There are several important things to remember when using PM suspend:
    64
    65 1) The uart drivers will disable the clocks to the UART blocks when
    66 suspending, which means that use of printascii() or similar direct
    67 access to the UARTs will cause the debug to stop.
    68
    69 2) Whilst the pm code itself will attempt to re-enable the UART clocks,
    70 care should be taken that any external clock sources that the UARTs
    71 rely on are still enabled at that point.
    72
    73
    74 Configuration
    75 -------------
    76
    77 The S3C2410 specific configuration in `System Type` defines various
    78 aspects of how the S3C2410 suspend and resume support is configured
    79
    80 `S3C2410 PM Suspend debug`
    81
    82 This option prints messages to the serial console before and after
    83 the actual suspend, giving detailed information on what is
    84 happening
    85
    86
    87 `S3C2410 PM Suspend Memory CRC`
    88
    89 Allows the entire memory to be checksummed before and after the
    90 suspend to see if there has been any corruption of the contents.
    91
    92 This support requires the CRC32 function to be enabled.
    93
    94
    95 `S3C2410 PM Suspend CRC Chunksize (KiB)`
    96
    97 Defines the size of memory each CRC chunk covers. A smaller value
    98 will mean that the CRC data block will take more memory, but will
    99 identify any faults with better precision
    100
    101
    102 Document Author
    103 ---------------
    104
    105 Ben Dooks, (c) 2004 Simtec Electronics
    106