WLAN and Disk LEDs blink when suspending/resuming

[wad]

On an XO-1.5 A1 prototype, the WLAN and Disk activity (previously disk flashes on and off (in rough synchrony with the power supply LEDs) as the system suspends and resumes using Open Firmware's rtc_wackup command. This is rather annoying if it happens under Linux as well.

The WLAN LED is currently driven by a GPIO pin, which is powered by the +3.3v supply (turned off in suspend). The signal is active high --- when it is turned off, the LED is turned off. This GPIO pin should probably be set to off early in the OFW boot/resume process.

The Disk activity light on the A1 prototypes is actually driven directly by the Phison disk controller, but in B1 and later prototypes using SD storage it will be controlled by the SD driver through the GPIO pin (hopefully!) Hence is is grouped with the WLAN signal as one that should be initialized very early in the boot sequence.

[wmb@…]

It appears that the rev-B boards have a redesigned circuit so the default state of that GPIO causes the LED to be off. That's good, because when I set the GPIO low in the early startup code to turn the LED off for A-test boards, the LED still flashes noticeably. I'm not sure that it will be feasible to turn it off quickly enough to avoid visible flashing.

Nevertheless, I have modified the early startup code to explicitly set that GPIO pin low for rev A, high (the default) for rev B. On B, the LED remains off during suspend cycles. On A, it flashes despite the code change.

[wmb@…]

On B2, the WLAN and Disk LEDs are not blinking on suspend, but the camera LED comes on after a resume.

Ah, the camera LED is a side effect of the serial being enabled. If you remove the SERIAL_EN jumper and reboot, the camera LED stays off, even after a resume.

So I'm closing this ticket as not being relevant to the real hardware.