On 4 March 2015 at 16:17, Siarhei Siamashka siarhei.siamashka@gmail.com wrote:
On Tue, 03 Mar 2015 08:17:56 +0000 Ian Campbell ijc+uboot@hellion.org.uk wrote:
On Mon, 2015-03-02 at 00:07 +0200, Siarhei Siamashka wrote:
Just one suggestion. It would be really nice if the Debian installer could present itself on all the available consoles, so that the user can use any of them for providing input to the installer.
There is some reason why d-i doesn't do this by default. I think it's to do with bricking or otherwise interfering with devices attached to serial ports e.g I think Braille terminals were mentioned, but I suppose any random device might not like getting random strings of characters.
There could be perhaps a fake kernel cmdline option to specify the exact list of consoles to be used by the Debian installer?
Otherwise there will be a need to provide separate SD card images for the HDMI console (for the Raspberry Pi wannable competitors), the UART serial console (A10/A20 development boards without HDMI) and the USB OTG serial gadget console (for the tablets without HDMI). Instead of just having only a single SD card image to handle everything automatically.
I've backported DT the /chosen/stdout-path support to the kernel a while ago and I thought together with Hans' u-boot patches to populate this field with the right thing then console selection would Just Work(tm).
I need to check this new feature myself, especially whether it can do user input handling.
At least for HDMI vs. UART since I'm not quite sure how the OTG gadget console is presented to Linux and whether it falls into this stuff correctly.
It should be seen as just one more /dev/tty* entry (maybe USB or ACM).
My original plan from
http://lists.denx.de/pipermail/u-boot/2015-January/202306.htmlwas to make the bootable SD card just drop into the FEL mode in the case if an A13/A23 SoC is detected or if there is no HDMI monitor connected. Then a custom application running on a desktop PC could upload a custom SPL for the only purpose of identifying the DRAM size and bus width. Then present a choice of the possibly matching devices to the user, boot the system via FEL, run hardware reliability tests and move on to preparing the rootfs.
But with the Debian installer, this becomes somewhat more difficult. Because we need a way of handling user input during the installation (for the language selection, time zone, and other things).
For things selectable from a menu it might be possible to use the volume and power keys as the Android recovery does.
Driver for the power key is already in u-boot. It's just not hooked up to provide input.
However with the new USB OTG code from Hans hopefully coming into the Linux kernel, we can have everything much easier and more unified :-) Basically, the serial port over USB should work fine even in Windows (at least it works for the Arduino people):
http://arduino.cc/en/Guide/WindowsAnd because the BROM is able to use USB OTG for the FEL mode on all sunxi devices, the serial console over USB should also work in a generic image without any special device dependent configuration.
I pretty much use only the OTG port when I boot GNU/Linux on a tablet. yes, I can get display output but any input has to come over OTG so I use ethernet gadget and ssh.
That also happens to cover downloading stuff in case the WiFi chipset is not supported. I have yet to see an Allwinner tablet with supported touchscreen.
Thanks
Michal