XO1.5 SD suspend

This describes the current setup for testing WLAN SD suspend/resume on prototypes of the XO-1.5 laptop.

Software Installation

You should start by obtaining the OS31 Linux image for the XO-1.5 from http://dev.laptop.org/~cjb/f11-1.5/os31/os31.zd.

1. Place the image on a USB stick, and insert it into the XO-1.5 laptop's USB port.
2. Boot the laptop, pressing the escape key ('X' in upper left hand corner of keyboard) within a few seconds after boot to enter Open Firmware (OFW).
3. To install onto the internal SD card, type:

fs-update u:\os31.zd

Now upgrade the kernel to one supporting Marvell's SD patches. The following sequence of commands should work:

wget http://dev.laptop.org/~dilinger/olpc-2.6.30/kernel-2.6.30_xo1.5-20091005.1546.1.olpc.61c1a98.i586.rpm
wget http://dev.laptop.org/~dilinger/olpc-2.6.30/kernel-firmware-2.6.30_xo1.5-20091005.1546.1.olpc.61c1a98.i586.rpm
rpm -ivh kernel-*
reboot

Hardware Modification

WLAN SDIO slot

The internal WLAN SD slot has a problem maintaining power during suspend. This modification is only necessary when testing the internal slot. The external SD card slot should function fine during suspend.

In order to disconnect the SD_PWOFF signal, preventing it from powering off the WLAN card in suspend, you should remove Q38. This is in an SOT-323 package, located on the "bottom" side of the motherboard (the same side as the processor) right below the WLAN card connector.

Serial Port

You will also need to connect a serial terminal, as the laptop display doesn't work after resume. It should be connected to J3, and JP1 (immediately behind J3) will need pin 1 shorted to pin 3 to enable the serial port.

Test Procedure

If modified by removing Q38 and using the internal WLAN card, the laptop must be powered down to power cycle the WLAN (not rebooted).

Boot the laptop. Due to a problem with OS31, it will halt in Open Firmware. Boot Linux by typing:

boot int:\olpc.fth

When Linux has booted, you can place the system into suspend by typing:

echo mem > /sys/power/state

It may take a few seconds to suspend if there are filesystem modifications that have to be flushed to non-volatile storage.

All commands after suspending HAVE to be typed through the serial port, as there is currently a bug with the video driver that prevents use of the display after resuming.

In order to wake the laptop from suspend, press the power button. This should bring you back to a Linux prompt.

Using interactive OFW

This requires a special kernel patch that is not included in the above software.

This kernel will complete the Linux suspend operations (calling all drivers), the drop the system into OFW right before actually suspending the hardware. You should see the "ok" prompt, although it may take a few seconds if there are filesystem modifications that have to be flushed to non-volatile storage.

All commands after this HAVE to be typed through the serial port.

In order to actually finish suspending the system, type:

resume

In order to wake the laptop from suspend, press the power button. This will bring you back to an OFW prompt ("+rok"). In order to start Linux executing again, type "resume" one more time. This should bring you back to a Linux prompt.

Exploring from Open Firmware

While we are mainly dropping into OFW on suspend and resume in order to allow for orderly testing (OFW by default ignores SCI wakeup events, which tend to wake Linux at random times), it is possible to explore the state of hardware registers or manually trigger a suspend (without returning to Linux).

You can set up to examine registers in the SD controller using these commands:

ok select /sd  0 3 set-address  map-regs

Now you can read the contents of the registers using the cw@ (config-word-read) command (which takes a register offset from the stack as an argument):

ok 2c cw@ .

You can modify the contents of a register using the cw! (config-word-write) command (which takes a register offset and a value from the stack as arguments).

In order to manually trigger a suspend, type:

ok select /wlan
ok 2400 404 pw!

Monitoring

The signals to the internal WLAN card may easily be probed at the WLAN connector:

1. SD_CLK
2. WLAN_3.3V
3. SD_CMD
4. GND
5. SD_DAT0
6. RESET#
7. SD_DAT1
8. N.C.
9. SD_DAT2
10. POWER_DOWN#
11. CARD_DETECT#
12. N.C.
13. SD_DAT3
14. ...

The signals on odd pins are accessible from the "bottom" side of the motherboard (the side with the processor). The signals on even pins are only accessible from the top side of the motherboard.