Perfect Hack For Mstar
the evaluation kits all use emmc memory instead of microsd cards, so i had to switch the bus widths over to 8 bits. the next problem i had is that the write-protect gpio signal on the sdmmc peripheral driver doesnt respect your device tree settings and is always enabled. if this pin isnt shorted to gnd, linux will think the chip has write protection enabled, causing it to throw a -30 error code (read-only filesystem error) on boot-up. i ended up adding a wp-inverted declaration in the device tree as a hack, but if i ever want to use that gpio pin for something else, ill have to do some more investigation.
Perfect Hack For Mstar
while the f1c100s / f1c200s can boot from spi nand or nor flash, sunxi-fel only has id support for spi nor flash. a bigger gotcha is that the flash-programming tool only supports 3-byte addressing, so it can only program the first 16mb of an spi flash chip. this really limits the sorts of applications you can do with this chip with the default memory layout, youre limited to a 10 mb rootfs partition, which isnt enough to install qt or any other large application framework. i hacked at the tool a bit to support 4-byte address mode, but im still having issues getting all the pieces together to boot, so its not entirely seamless.
dell almost exclusively uses mstar chips as monitor display driver ics. they used to use st / genesis chips but i can imagine the penny pinch hammer kicked in. dell probably doesnt even design any part of their monitors anymore regardless. havnt seem a single datasheet or any document from an mstar display ic. not sold at any legit vendor or distributor. not worth the trouble to implement.
https://www.oraclegale.com/group/oraclegale-group/discussion/761973f0-3946-49d9-8be4-9596ba7d5013