CI20 upstream

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This page contains details about the latest kernel branch running on the CI20.

It will be periodically updated to keep up to speed with the latest.

The current branch tracking mainline 3.18.3

Status of Linux Kernel Drivers


The CI20 uses the Ingenic JZ4780 SoC.

Ingenic provided a 3.0.8 kernel with reasonably functioning support for most peripherals on the JZ4780. development moves very quickly.

IMGTEC has reworked many drivers and forward ported others. already has support for JZ4740. However, JZ4740 has not been updated to use device-tree. JZ4780 and JZ4740 do share many features and peripherals. Hence, the best practice would be to augment the jz4740 drivers to work with the JZ4780.

3.16 branch was created to run the CI20 on a more recent kernel with that in mind. There was some work done on cosolidation to use the existing jz4740 drivers. But the core SoC parts were still disjoint.

After collaboration with the kernel community working on jz4740, jz4770, jz4780. 3.18 was rewritten with heavy emphasis on consolidation of the core SoC driver.

Core patches are in-flight.

There is still lots of work to be done. Please do contribute to kernel development. We are very welcoming and friendly on #ci20 chatroom and the mailing list


In-flight patch series for jz4780 core support in kernel can be seen here
Name State Path Notes 3.0.8 Notes 3.16 Notes 3.18 +
Clocks Works drivers/clk/jz47xx Could have common drivers/clk/ingenic for all SoCs with SoC specific binding using common components(?) Uses common clock framework with jz4740. Intended for upstream
CPUfreq 4770 has [1], but clock infrastructure is different. Ingenic kernel had [2] for 4780. Not ported to 3.16 yet.
Device Tree Mostly N/A Parsed on boot, but compiled into the kernel. Would be good to allow it to be passed from the bootloader. DT for jz4740 as well
DMA Mostly drivers/dma/dma-jz4780.c needs combining into dma-jz4740. Works, just missing priority support See [3]
GPIO Works drivers/pinctrl/pinctrl-jz4780.c should perhaps be in drivers/gpio/ (?)
IRQ Controller drivers/irqchip/irq-jz4780.c Very similar between SoCs (4740 has one bank, 60,70,80 has two banks) Consolidated work in 3.18 headed upstream
MXU Context
PinCtrl Mostly drivers/pinctrl/pinctrl-jz4780.c N/A Differs between SoCs. Functional, may need DT binding changes based on feedback from upstream. See also pinctrl-jz4770.c.
Power Controller (LPCR Register)
Power Off & Reset Works
RTC Works drivers/rtc/rtc-jz4740.c Consolidated with jz4740 Consolidated with jz4740
SMP Works Works Works
Watchdog Works Consolidated with jz4740

Peripheral drivers

Name State Path Notes 3.0.8 Notes 3.16 Notes 3.18+
ADC WIP Check branches on
Audio (ALSA) Works Check patches on!forum/mips-creator-ci20-dev Works. Uses jz4740 drivers with patches. i2s parts upstreamed. See [4] and [5]
Efuse Works drivers/misc/jz_efuse.c Works. Can read chip/serial id. Not linked with dm9000 for mac address. Upstream might face issues as yet another misc driver for eeprom. Efuse might need a subsystem talk etc
Ethernet Works drivers/net/ethernet/davicom/dm9000.c Requires regulator and reset GPIO support, see [6]. Patch upstreamed. See [7]
GPU External Kernel Module Works WIP. Requires major overhaul as kernel layer changed significantly from 3.0.8 to 3.18 for jz4780. The way clocks, regulators enabled. The way registers handled etc.. LCD and HDMI drivers changed completely.
HDMI WIP Resolution requires kernel recompile Check patches on!forum/mips-creator-ci20-dev See [8]. Needs atomic mode setting and universal plane update for upstreaming
I2C Works drivers/i2c/busses/i2c-jz4780.c 4740 has HW issue so uses gpio i2c instead. 4770 had [9] but unused so removed (also gave false positives on i2cdetect). Works. Not 100% clear if gives spurious errors like 4770. Some i2x tx abrts etc. See [10]
IPU 4770 has driver integrated with fbdev driver, see [11]. Plans to move to DRM+KVM but may take time.
IR Driver upstream drivers/media/rc/gpio-ir-recv.c GPIO, so use upstream GPIO driver
MMC Works drivers/mmc/host/jz4740_mmc.c Various changes needed, see [12]. Should not rename driver. Check whether affected by [13]. Works. Consolidation work needed before upstream. jz4740 has diverged. DMA driver differences block.
NAND Works Works. Reworked driver See [14]
PWM drivers/pwm/pwm-jz4740.c 4770 uses same driver as 4740. Maybe applicable to 4780 too. See [15].
Regulator Works Works. Based on i2c driver. Upstreamed. See [16]
SPI (SSI) None SPIO GPIO should work, but a dedicated driver for the SSI hardware in drivers/spi/ would be better.
UART Works Quirks: see patches [17] [18] See serial patches in series [19]. Works
USB (EHCI) Works Buggy.
USB (OHCI) Works Buggy.
USB(DWC) Works Upstream driver supports only host mode as of 3.15 Uses upstream driver. Sometimes gives overcurrent errors on dmesg. Gadget support needs consolidation with mainline.
VPU Driver aimed at 4770, see [20]. For samples see [21]. May be insecure (allows userland to do its own cache control and access TCSM banks). RemoteProc driver in progress, see [22].
Wifi WIP Check patches on!forum/mips-creator-ci20-dev Works. Uses some hacks to keep regulators on to enable the chip. Uses upstreamed driver and mmc/dma.
BT WIP Almost works. Uses some hacks to keep regulators on to enable the chip. Scans ok. File transfer presents a few issues. Possible not entirely kernels fault and bluez etc.

List of other possible issues when moving from 3.0.8 to 3.16+


If you are using the default debian rootfs on NAND and just update the kernel.

The NAND drivers between 3.0.8 and 3.16 are different. And detect different partition structures.

3.16 detects rootfs to be on mtd3.

While 3.0.8 detects rootfs to be on mtd1

So change the bootargs in uboot

setenv bootargs "console=ttyS4,115200 mem=256M@0x0  ubi.mtd=3 root=ubi0:root rootfstype=ubifs rw clock_ignore_unused"

Note: You might want to add another file in /boot instead of changing vmlinux.img

setenv bootcmd "mtdparts default; ubi part system; ubifsmount ubi:boot; ubifsload 0x88000000 uImage.3.18; bootm 0x88000000"

This way you can check your ci20 boots without messing the nand during a kernel upgrade.

Once checked


will save the environment


  • /etc/init.d/iw8103 is the startup script for the BT/Wifi firmware in the default rootfs.

If using 3.16/3.18, the script can cause the boot to hang unless the BT device is responding. Please move the script out of /etc/init.d or make sure the kernel is correct.

This is an issue with broadcoms patchram utility. It keeps trying. (Perhaps its some arguments passed to the script?)

Add "root=/dev/mmcblk0p1 rootwait" to bootargs in uboot if you wish to boot a rootfs from mmc.


GPU drivers rely on userland binaries and kernel module sources.

The work is on-going at IMG. Until the drivers are updated, using the GPU (openGL etc) will not be possible.

For normal usage, Xorg and framebuffer drivers do work.

The default xorg.conf is configured to load the powervr module. move that somewhere else/keep a copy. And use this xorg.conf

Note: Rename to xorg.conf. Don't leave it named xorg.conf.fbdev.

Place in /etc/X11/xorg.conf