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author | Dario Binacchi <dariobin@libero.it> | 2021-09-26 11:58:58 +0200 |
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committer | Tom Rini <trini@konsulko.com> | 2021-10-11 14:27:32 -0400 |
commit | 165e8fe5db64542d64fff6f81edb77c350e993cf (patch) | |
tree | bceaf7c3f0eead73a2ccfebe66dd0ccad26590ba /board | |
parent | 15a0411787e3ea70b93029500a644c1252bc4d0a (diff) | |
download | u-boot-165e8fe5db64542d64fff6f81edb77c350e993cf.zip u-boot-165e8fe5db64542d64fff6f81edb77c350e993cf.tar.gz u-boot-165e8fe5db64542d64fff6f81edb77c350e993cf.tar.bz2 |
clk: ti: add am33xx/am43xx spread spectrum clock support
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@libero.it>
Diffstat (limited to 'board')
0 files changed, 0 insertions, 0 deletions