From: Tom Rini <trini@konsulko.com>
To: Dario Binacchi <dariobin@libero.it>
Cc: u-boot@lists.denx.de, Lukasz Majewski <lukma@denx.de>
Subject: Re: [PATCH 3/3] clk: ti: add am33xx/am43xx spread spectrum clock support
Date: Mon, 11 Oct 2021 22:40:11 -0400 [thread overview]
Message-ID: <20211012024011.GT7964@bill-the-cat> (raw)
In-Reply-To: <20210926095858.31278-4-dariobin@libero.it>
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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@libero.it>
Applied to u-boot/master, thanks!
--
Tom
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prev parent reply other threads:[~2021-10-12 2:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-26 9:58 [PATCH 0/3] Add am33xx/am43xx spread spectrum clock support Dario Binacchi
2021-09-26 9:58 ` [PATCH 1/3] ARM: dts: am33xx-clocks: add spread spectrum support Dario Binacchi
2021-10-12 2:40 ` Tom Rini
2021-09-26 9:58 ` [PATCH 2/3] ARM: dts: am43xx-clocks: " Dario Binacchi
2021-10-12 2:40 ` Tom Rini
2021-09-26 9:58 ` [PATCH 3/3] clk: ti: add am33xx/am43xx spread spectrum clock support Dario Binacchi
2021-10-12 2:40 ` Tom Rini [this message]
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