Supported microSD cards/SD-C02G
Kingston SD-C02G works fine at good GSM coverage with the following kernel parameters here (GTA02 with GPS capacitor fix on uSD slot):
Lower drive strength or or higher clock speed cause unreliable behavior if the GSM modem is activated (either directly after entering the PIN, when making a call, or using GPRS - more often while having bad GSM reception and using GPRS):
Sep 15 14:15:20 debian-gta02 kernel: mmcblk0: error -84 sending read/write command
Sep 15 14:15:20 debian-gta02 kernel: glamo-mci glamo-mci.0: Error after cmd: 0x4304
Drive strength of 0 at glamo_mci.sd_max_clk=10000000 is pretty reliable at normal operation (at good GSM reception), but still fails sometimes when GPRS is activated. Drive strength of 2 still fails repeatably when using GSM in less populated area or when accessing SD card directly after entering PIN.
(last verified using 2008.8 and newer daily kernel versions)
Another problem with this card is that with a fairly new kernel (andy-tracking commit de8460932576502fb6bf61968a37c4d2aed2d6e2), to get wifi card properly recognized in the kernel, you have to unbind/bind the sdio bus like this:
echo s3c2440-sdi >/sys/bus/platform/drivers/s3c2440-sdi/unbind
echo s3c2440-sdi >/sys/bus/platform/drivers/s3c2440-sdi/bind
- SD idle clock = on does not prevent the errors
- Errors occur almost every time when loading things from SD card while entering PIN, even at drive strength of 3 and clock speed of 2.5 Mhz
- Verify the card is indeed the only one affected (ruling out FreeRunner HW problems is hard, only got one)
- Try to reproduce that GSM affects SD data lines themselves, not only the card
- Verify that screen sometimes filling with random data when card fails is related to failing card, and not to failing glamo which in turn results in card errors.
- Find out if it also happens in areas without GSM buzz.