GalaxyTab2BootloaderInterface » History » Revision 4
Revision 3 (Denis 'GNUtoo' Carikli, 03/03/2021 05:18 PM) → Revision 4/5 (Denis 'GNUtoo' Carikli, 03/03/2021 05:22 PM)
h1. GalaxyTab2BootloaderInterface GT-P3100Bootloader {{toc}} h2. Boot log At boot, when pressing the power button for a short time we get: <pre> $ picocom -b 115200 /dev/ttyUSB1 picocom v3.1 port is : /dev/ttyUSB1 flowcontrol : none baudrate is : 115200 parity is : none databits are : 8 stopbits are : 1 escape is : C-a local echo is : no noinit is : no noreset is : no hangup is : no nolock is : no send_cmd is : sz -vv receive_cmd is : rz -vv -E imap is : omap is : emap is : crcrlf,delbs, logfile is : none initstring : none exit_after is : not set exit is : no Type [C-a] [C-h] to see available commands Terminal ready Texas Instruments X-Loader 1.41 (Jun 13 2012 - 22:11:09) Uboot-loading from Emmc Starting OS Bootloader from EMMC ... </pre> Here the device boots, but if the button isn't pressed long enough it shuts down. When pressing it for a longer time we get: <pre> $ picocom -b 115200 /dev/ttyUSB1 picocom v3.1 port is : /dev/ttyUSB1 flowcontrol : none baudrate is : 115200 parity is : none databits are : 8 stopbits are : 1 escape is : C-a local echo is : no noinit is : no noreset is : no hangup is : no nolock is : no send_cmd is : sz -vv receive_cmd is : rz -vv -E imap is : omap is : emap is : crcrlf,delbs, logfile is : none initstring : none exit_after is : not set exit is : no Type [C-a] [C-h] to see available commands Terminal ready Texas Instruments X-Loader 1.41 (Jun 13 2012 - 22:11:09) Uboot-loading from Emmc Starting OS Bootloader from EMMC ... g_nRebootReason = 0x100000 Kernel @ 81808000 (4524144 bytes) Ramdisk @ 82800000 (994957 bytes) set_lcd_panel_id: panel_adc=805 *** ltn070nl01_power_on *** lcd_pannel_id=3 AST_POWERON </pre> Here @AST_POWERON@ probably means that there is a GPIO that can switch between the OMAP4 UART and the modem UART, and that at some point during the boot it's switched to the modem. I tried to type AT commands like @AT@ but I got no response. Maybe it's because I use the wrong voltage for the UART. Maybe I need to reset the modem through AT commands. TODO: * Measure the UART voltage somehow (output only ones and try to measure it) * Try to see if it responds to AT reset and verbose commands h2. Xloader Note that there is no u-boot here despite what the print says: the Galaxy Tab 2 use xloader, and the source code of xloader is available for the Galaxy Tab 2, and its prints mention u-boot regardless of the bootloader that it loads. Unfortunately the xloader it uses is signed, so even if it's license is free software we can't change it. As users are denied the right to run modified versions, we consider the result nonfree even if the license is free.