CI20 upstream

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

https://github.com/MIPS/CI20_linux

Status of Linux Kernel Drivers

Overview

The CI20 uses the Ingenic JZ4780 SoC.

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

Kernel.org development moves very quickly.

IMGTEC has reworked many drivers and forward ported others.

kernel.org 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

Core

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	still needs combining
GPIO	Works	drivers/pinctrl/pinctrl-jz4780.c		should perhaps be in drivers/gpio/ (?)
Hotplug
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 https://github.com/ZubairLK/CI20_linux
Audio (ALSA)	Works			Check patches on https://groups.google.com/forum/#!forum/mips-creator-ci20-dev	Works. Uses jz4740 drivers with patches. Some in flight. Some awaiting jz4780 core
Camera
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 [3].	Patch upstreamed.
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 https://groups.google.com/forum/#!forum/mips-creator-ci20-dev	Resolution requires xorg/bootargs. Needs work for consolidation with upstream.
I2C	Works	drivers/i2c/busses/i2c-jz4780.c		4740 has HW issue so uses gpio i2c instead. 4770 had [4] but unused so removed (also gave false positives on i2cdetect).	Works
IPU				4770 has driver integrated with fbdev driver, see [5]. 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 [6]. Should not rename driver. Check whether affected by [7].	Works. Consolidation work needed before upstream. jz4740 has diverged. DMA driver differences block.
NAND	Works			Works. Reworked driver	Works. Reworked driver
PWM		drivers/pwm/pwm-jz4740.c		4770 uses same driver as 4740. Maybe applicable to 4780 too. See [8].
Regulator	Works			Works. Based on i2c driver.	Works. Based on i2c driver.
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 [9] [10] need moving to wrapper driver, like 8250_dw and mediatek which can be common between Ingenic SoCs.	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 [11]. For samples see [12]. May be insecure (allows userland to do its own cache control and access TCSM banks). RemoteProc driver in progress, see [13].
Wifi	WIP			Check patches on https://groups.google.com/forum/#!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+

Bluetooth

• /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.

SGX

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