- ryang2678 (Decatf)
We avoid flashing the
boot partition because a corrupted kernel would irreversibly brick the Ouya. We use a tool called Ouya BootMenu (source) that allows us to chain load the postmarketOS kernel using kexec.
There are two mechanisms to output audio through HDMI.
- Tegra30 HDA
- Tegra30 SPDIF
The HDA device is what is used by the downstream kernel and stock Ouya Android ROM. The SPDIF device only outputs to the left channel.
Audio output through the HDA device works on the downstream kernel. The HDA device is card 0 device 3. It can be tested by running
speaker-test -Dhw:0,3 -c 2. The SPDIF device is card 1 device 0. It can be tested by running
speaker-test -Dhw:1,0 -c 2.
The mainline kernel has a tegra30-hda driver but it isn't working on Ouya. There is no upstreamed driver for the Tegra30 SPDIF device.
The Tegra30 HDA driver writes 4 frames and then hangs.
$ speaker-test -Dhw:0,3 -c 2 speaker-test 1.1.8 Playback device is hw:0,3 Stream parameters are 48000Hz, S16_LE, 2 channels Using 16 octaves of pink noise Rate set to 48000Hz (requested 48000Hz) Buffer size range from 64 to 16384 Period size range from 32 to 8192 Using max buffer size 16384 Periods = 4 was set period_size = 4096 was set buffer_size = 16384 0 - Front Left snd_pcm_hw_writei hw_writei: frames = 4096, xferi.result = 4096, err = 0 snd_pcm_hw_writei hw_writei: frames = 4096, xferi.result = 4096, err = 0 snd_pcm_hw_writei hw_writei: frames = 4096, xferi.result = 4096, err = 0 snd_pcm_hw_writei hw_writei: frames = 4096, xferi.result = 4096, err = 0 snd_pcm_hw_writei hw_writei: frames = 4096, xferi.result = -5, err = -5 Write error: -5,I/O error xrun_recovery failed: -5,I/O error Transfer failed: I/O error
The kernel PCM framework in
sound/core/pcm_native.c has a timeout waiting for the device to respond.
[ 691.115717] tegra-hda 70030000.hda: playback write error (DMA or IRQ trouble?)
It is uncertain why the HDA device isn't working on mainline. Possible avenues to explore:
- Compare pinmuxes to downstream kernel.
- Are the necessary clocks enabled and at the correct frequency?
A random MAC address is generated by the kernel at each boot. This is because the smsc9500 Ethernet device does not have a valid mac address stored in EEPROM. To set a consistent MAC address, create the file
/etc/udev/rules.d/99-mac-address.rules with the following udev rule.
ACTION=="add", SUBSYSTEM=="net", KERNEL=="eth0", RUN+="/sbin/ip link set dev %k address f6:23:f0:42:98:cf"
- The Ouya uses a BCM4330 radio chip for wifi and bluetooth. The downstream and mainline kernel use the same wifi firmware. The firmware shipped with the device is the only known firmware to work with the Ouya. The BCM4330 firmware in
linux-firmwaredoes not work.
- Two later releases (the completely white special edition and completely black 2nd generation) allegedly use a BCM4334 chipset. This needs to be implemented and tested at a future date.
On the mainline kernel, display resolutions above 1280x720 are glitchy. The GPU is dependent on memory bandwidth but EMC scaling is not implemented in mainline. The Ouya bootloader sets the memory to 400 Mhz. Higher display resolutions work a bit better when the memory is set to 800Mhz but it is still glitchy.
The Ouya is missing HDMI CEC support at the hardware design level.
- Splash screen doesn't appear
- Hildon doesn't work?
- USB booting needs to be tested
How to enter flash mode
1. Connect Ouya to PC
adb reboot recovery to enter recovery (or
adb reboot bootloader to enter bootloader for fastboot commands)
2. Turn on Ouya, then press the power button many times until it scrolls to Bootloader, and then wait until the boot menu disappears.
3. Run the following using pmbootstrap:
$ pmbootstrap init $ pmbootstrap install $ pmbootstrap export $ pmbootstrap flasher flash_rootfs
4. Reboot Ouya, then press the power button many times until it scrolls to Recovery, and then wait until CWM appears.
6. Using CWM menu options, mount /data partition.
7. Copy postmarketOS boot.img to /sdcard as altboot.img:
$ adb push /tmp/postmarketOS-export/boot.img-ouya-ouya /sdcard/altboot.img
8. Reboot Ouya, then press the power button many times until it scrolls to Alternate Boot, and then wait until postmarketOS appears.
Using data partition as rootfs
It is much more usable to flash rootfs to the data partition which is around 5.7GB in size.
Flashing to the data partition
Specify the partition to flash rootfs to with the
$ pmbootstrap flasher flash_rootfs --partition userdata
$ adb push /tmp/postmarketOS-export/boot.img-ouya-ouya /system/boot.img
Updating the kernel
apk package manager updates the kernel package (e.g.
linux-ouya-ouya-mainline) then the
boot.img will be regenerated with the new kernel. Run the following commands on device to install the updated
$ mkdir /system $ mount /dev/mmcblk1p3 /system $ cp /boot/boot.img-ouya-ouya /system/boot.img