Samsung Z1 (samsung-kiran)

Contributors

 * peremen

How to enter flash mode
Similar as Samsung's Android counterparts:
 * Hold +  +  buttons to enter flash mode.
 * Hold +  +  buttons to enter recovery mode.

/proc/cmdlines for different power on reasons:
 * Normal mode:
 * Recovery mode:
 * Plugging in charger:

Installation/Known Problems
Technically similar as Samsung's Android counterparts, however, there are some caveats. The stock Tizen boot image uses dzImage, basically vmlinuz + Spreadtrum dtb binary (can generate using dtbtool-sprd) with custom header. Because Tizen kernel does not enable initramfs, and S-BOOT on this device seems to lack support of it, we are using isorec. The current postmarketOS kernel will use KERNEL to store dzImage, RAMDISK to store initramfs. Make sure to flash both partitions when going from Tizen to postmarketOS and vice versa.

Booting non-stock kernel image will show a red exclamation mark on the top left of boot screen.

The sprdfb driver of Tizen kernel is different from Android devices using the same SoC: it has DRM driver for this SoC, predates what is in the mainline. Graphics memory management seems to be done using libtbm in Tizen and X.org proprietary driver. There is no memory region for sprdfb driver mentioned in the .dts file, thus mmap to the framebuffer returns only an error. The postmarketOS kernel patch manually includes the memory region in the .dts file and modifies the memory allocation to make framebuffer work. Lack of proper Spreadtrum datasheet makes further progress hard.

Components

 * UART: 1.8 V, See Serial debugging:Cable schematics. 150K Ohm resistor enables serial console.
 * Wi-Fi: Broadcom BCM4343S, requires firmware (from either Tizen or any other)
 * GPS: Broadcom BCM47520
 * MUIC: Richtek SM5504
 * Charger: Richtek SM5701