Hello,
I have made a custom board based of am572x-evm and beagleboard x15.
In the "u-boot" .. arch/arm/mach-omap2/omap5/hw_data.c
there are the clock definitions like
/* ABE M & N values with sysclk2(22.5792 MHz) as input */
static const struct dpll_params
abe_dpll_params_sysclk2_361267khz[NUM_SYS_CLKS] = {
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 12 MHz */
{16, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 20 MHz */
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 16.8 MHz */
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 19.2 MHz */
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 26 MHz */
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 27 MHz */
{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, /* 38.4 MHz */
};
I think that comments are a little bit confusing, because wich clock source is used? It is the 20Mhz clock source on OSC0 or OSC1 ?
A few months ago I asked on this forum which clock sources is needed, the answer was the OSC1 were optional. https://e2e.ti.com/support/processors/f/791/t/743176
On my custom board I don`t use the OSC1!
I tought that the sysboot pins 8 and 9 would indicate after starting up the processor which clock speed is selected for SYS_CLK1 (OSCO0).
Trough the SYSBOOT8/9 it is only possible to select 4 clock speed but in the structure there are 7 defined.
There are a general equation for the clocks?
for example to calculate the clock for structure "core_dpll_params_2128mhz_dra7xx"
I get 2128 MHz if I calculate 266MHz / 4 * 2 * 1
-> OSCO{1,2} * m / n * m2 * m3 ?
And what about structure static const struct dpll_params per_dpll_params_768mhz[NUM_SYS_CLKS
is that calcultion correct?
16.8 Mhz * 160 / 6 * 4 * 3 * 6 * 4 * (2+1) ???
I dont get the expected 768Mhz just only 774 Mhz what is wrong?
