[PATCH 3/3] clk: ti: add am33xx/am43xx spread spectrum clock support

Tom Rini trini at konsulko.com
Tue Oct 12 04:40:11 CEST 2021

On Sun, Sep 26, 2021 at 11:58:58AM +0200, Dario Binacchi wrote:

> The patch enables spread spectrum clocking (SSC) for MPU and LCD PLLs.
> As reported by the TI spruh73x/spruhl7x RM, SSC is only supported for
> the DISP/LCD and MPU PLLs on am33xx/am43xx. SSC is not supported for
> DDR, PER, and CORE PLLs.
> Calculating the required values and setting the registers accordingly
> was taken from the set_mpu_spreadspectrum routine contained in the
> arch/arm/mach-omap2/am33xx/clock_am33xx.c file of the u-boot project.
> In locked condition, DPLL output clock = CLKINP *[M/N]. In case of
> SSC enabled, the reference manual explains that there is a restriction
> of range of M values. Since the clk_ti_am3_dpll_round_rate() attempts
> to select the minimum possible N, the value of M obtained is not
> guaranteed to be within the range required. With the new "ti,min-div"
> parameter it is possible to increase N and consequently M to satisfy the
> constraint imposed by SSC.
> Link: https://lore.kernel.org/r/20210606202253.31649-6-dariobin@libero.it
> Signed-off-by: Dario Binacchi <dariobin at libero.it>

Applied to u-boot/master, thanks!

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