On 20/09/2013 01:36, Marek Vasut wrote:
In case the MX23/MX28 is switched into JTAG mode via the BootMode select switches, the BootROM bypasses the CPU core registers initialization. This in turn means that the Stack Pointer (SP) register is not set as it is in every other mode of operation, but instead is only zeroed out.
To prevent U-Boot SPL from crashing in this obscure JTAG mode, configure the SP to point at the CONFIG_SYS_INIT_SP_ADDR if the SP is zeroed out.
Note that in case the SP is already configured, we must preserve that exact SP value and must not modify it. This is important since in every other mode but the JTAG mode, the SPL returns into the BootROM and BootROM in turn loads U-Boot itself. If the SP were to be corrupted, the BootROM won't be able to continue it's operation after returned from SPL and the system would crash.
Finally, add the JTAG mode switch identifier, so it's not recognised as Unknown mode.
Signed-off-by: Marek Vasut marex@denx.de Cc: Stefano Babic sbabic@denx.de Cc: Fabio Estevam fabio.estevam@freescale.com Cc: Otavio Salvador otavio@ossystems.com.br
Applied to u-boot-imx, -next branch, thanks !
Best regards, Stefano Babic