GSENSOR_3V3 voltage drop

Christoph Mair ml at
Mon Aug 24 19:50:10 CEST 2009

> Sven wrote:
> 2009/8/24 Christoph Mair <ml at>:
> > GPD12/13 (G1_CS and G2_CS) remain high (3V3) after suspend.
> I assume you mean it stays high while in suspend? This is really
> strange, as the last action when suspending the accels is:
> s3c2410_gpio_setpin(pdata->pin_chip_select, 0);
> s3c2410_gpio_setpin(pdata->pin_clk, 0);
> s3c2410_gpio_setpin(pdata->pin_mosi, 0);
> /* misnomer: it is a pullDOWN in 2442 */
> s3c2410_gpio_pullup(pdata->pin_miso, 1);
> Which is exactly what we want. However, I don't see how the
> chip_select (GPD12 and GPD13) can be high then... Are you really sure
> you don't mess with them in your driver? If not, please also post your
> findings (GPD12+GPD13 high during suspend) to the openmoko-kernel
> mailing list, as there are more capable kernel guys. ;-)

To verify my measurements I did:
- remove my own HW which could probably leak current
- reboot the phone to be sure my driver is not loaded (btw. it does never 
touch gpio lines, just basic i2c stuff)
- check for autoloaded modules:
- check kernel version:
	uImage-moredrivers-GTA02_andy-tracking-197d20a357d6a884.bin (including 3V3-
- switch the phone on: GPD12/13 go high
- press the power switch and wait until the phone has suspended:
	GPD13 remains at high level, the voltage drops from 3.4V to 3.28V at G2_CS
	GPD12 seems to be down
	SENSOR_3V3 drops to 2.4V
- press the power switch again to resume the phone:
	G1_CS rises to 3.40V
	G2_CS rises to 3.40V
	SENSOR_3V3 rises to 3.38V

I'm quite sure that yesterday, during suspend, G1_CS was high too. Today I 
could not verify this, but G2_CS is definitively high during suspend.


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