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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/README.t4240qds | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/doc/README.t4240qds b/doc/README.t4240qds index 677d120..19e8a8a 100644 --- a/doc/README.t4240qds +++ b/doc/README.t4240qds @@ -96,3 +96,27 @@ The addresses in brackets are physical addresses. 0x0_ffff_f000 (0x0_7fff_fff0) - 0x0_ffff_ffff 4KB Boot page translation for secondary cores The physical address of the last (boot page translation) varies with the actual DDR size. + +Voltage ID and VDD override +-------------------- +T4240 has a VID feature. U-boot reads the VID efuses and adjust the voltage +accordingly. The voltage can also be override by command vdd_override. The +syntax is + +vdd_override <voltage in mV>, eg. 1050 is for 1.050v. + +Upon success, the actual voltage will be read back. The value is checked +for safety and any invalid value will not adjust the voltage. + +Another way to override VDD is to use environmental variable, in case of using +command is too late for some debugging. The syntax is + +setenv t4240qds_vdd_mv <voltage in mV> +saveenv +reset + +The override voltage takes effect when booting. + +Note: voltage adjustment needs to be done step by step. Changing voltage too +rapidly may cause current surge. The voltage stepping is done by software. +Users can set the final voltage directly. |