Using environmental variable "ddr_interactive" to activate interactive DDR debugging seomtiems is not enough. For example, after updating SPD with a valid but wrong image, u-boot won't come up due to wrong DDR configuration. By enabling key press method, we can enter debug mode to have a chance to boot without using other tools to recover the board.
CONFIG_FSL_DDR_INTERACTIVE needs to be defined in header file. To enter the debug mode by key press, press key 'd' shortly after reset, like one would do to abort auto booting. It is fixed to lower case 'd' at this moment.
Signed-off-by: York Sun yorksun@freescale.com --- arch/powerpc/cpu/mpc8xxx/ddr/main.c | 6 ++++-- doc/README.fsl-ddr | 7 +++++++ 2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/cpu/mpc8xxx/ddr/main.c b/arch/powerpc/cpu/mpc8xxx/ddr/main.c index d6b73c7..a33c9e2 100644 --- a/arch/powerpc/cpu/mpc8xxx/ddr/main.c +++ b/arch/powerpc/cpu/mpc8xxx/ddr/main.c @@ -532,9 +532,11 @@ phys_size_t fsl_ddr_sdram(void)
/* Compute it once normally. */ #ifdef CONFIG_FSL_DDR_INTERACTIVE - if (getenv("ddr_interactive")) + if (getenv("ddr_interactive")) { total_memory = fsl_ddr_interactive(&info); - else + } else if (tstc() && (getc() == 'd')) { /* we got a key press of 'd' */ + total_memory = fsl_ddr_interactive(&info); + } else #endif total_memory = fsl_ddr_compute(&info, STEP_GET_SPD, 0);
diff --git a/doc/README.fsl-ddr b/doc/README.fsl-ddr index 3992640..59583b3 100644 --- a/doc/README.fsl-ddr +++ b/doc/README.fsl-ddr @@ -268,6 +268,13 @@ be activated by saving an environment variable "ddr_interactive". The value doesn't matter. Once activated, U-boot prompts "FSL DDR>" before enabling DDR controller. The available commands can be seen by typing "help".
+Another way to enter debug mode without using environment variable is to send +a key press during boot, like one would do to abort auto boot. To save booting +time, no additioal delay is added so the window to send the key press is very +short. For example, user can send the key press using reset command followed by +hitting enter key twice. In case of power on reset, user can keep hitting any +key while applying the power. + The example flow of using interactive debugging is type command "compute" to calculate the parameters from the default type command "print" with arguments to show SPD, options, registers