Re: [PATCH 4/4] clk: ti: add am33xx spread spectrum clock support

[Grygorii Strashko]

On 18/03/2021 09:38, Dario Binacchi wrote:
> Hi Grygorii,
>
> > Il 16/03/2021 12:52 Grygorii Strashko <grygorii.strashko@xxxxxx> ha scritto:
> >
> >   
> > On 14/03/2021 17:12, Dario Binacchi wrote:
> > > The patch enables spread spectrum clocking (SSC) for MPU and LCD PLLs.
> > > As reported by the TI spruh73x RM, SSC is only supported for the
> > > DISP/LCD and MPU PLLs on am33xx device. 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 AM335x reference manual explains that there is a
> > > restriction of range of M values. Since the omap2_dpll_round_rate
> > > routine 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.
> > >
> > > Signed-off-by: Dario Binacchi <dariobin@xxxxxxxxx>
> > >
> > > ---
> > >
> > >    arch/arm/boot/dts/am33xx-clocks.dtsi |  4 +-
> > >    drivers/clk/ti/dpll.c                | 41 ++++++++++++++
> > >    drivers/clk/ti/dpll3xxx.c            | 85 ++++++++++++++++++++++++++++
> > >    include/linux/clk/ti.h               | 24 ++++++++
> > >    4 files changed, 152 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/arm/boot/dts/am33xx-clocks.dtsi b/arch/arm/boot/dts/am33xx-clocks.dtsi
> > > index e7bbbf536a8c..a02e0b1229a4 100644
> > > --- a/arch/arm/boot/dts/am33xx-clocks.dtsi
> > > +++ b/arch/arm/boot/dts/am33xx-clocks.dtsi
> > > @@ -164,7 +164,7 @@
> > >    		#clock-cells = <0>;
> > >    		compatible = "ti,am3-dpll-core-clock";
> > >    		clocks = <&sys_clkin_ck>, <&sys_clkin_ck>;
> > > -		reg = <0x0490>, <0x045c>, <0x0468>, <0x0460>, <0x0464>;
> > > +		reg = <0x0490>, <0x045c>, <0x0468>;
> > >    	};
> > >    
> > >    	dpll_core_x2_ck: dpll_core_x2_ck {
> > > @@ -204,7 +204,7 @@
> > >    		#clock-cells = <0>;
> > >    		compatible = "ti,am3-dpll-clock";
> > >    		clocks = <&sys_clkin_ck>, <&sys_clkin_ck>;
> > > -		reg = <0x0488>, <0x0420>, <0x042c>;
> > > +		reg = <0x0488>, <0x0420>, <0x042c>, <0x0424>, <0x0428>;
> > >    	};
> >
> > You can't mix DT vs code.
>
> Right, I forgot to remove it during a rebase of the series.
>
> > >    
> > >    	dpll_mpu_m2_ck: dpll_mpu_m2_ck@4a8 {
> > > diff --git a/drivers/clk/ti/dpll.c b/drivers/clk/ti/dpll.c
> > > index d6f1ac5b53e1..2738417a47b7 100644
> > > --- a/drivers/clk/ti/dpll.c
> > > +++ b/drivers/clk/ti/dpll.c
> > > @@ -290,7 +290,9 @@ static void __init of_ti_dpll_setup(struct device_node *node,
> > >    	struct clk_init_data *init = NULL;
> > >    	const char **parent_names = NULL;
> > >    	struct dpll_data *dd = NULL;
> > > +	int ssc_clk_index;
> > >    	u8 dpll_mode = 0;
> > > +	u32 min_div;
> > >    
> > >    	dd = kmemdup(ddt, sizeof(*dd), GFP_KERNEL);
> > >    	clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL);
> > > @@ -345,6 +347,27 @@ static void __init of_ti_dpll_setup(struct device_node *node,
> > >    	if (dd->autoidle_mask) {
> > >    		if (ti_clk_get_reg_addr(node, 3, &dd->autoidle_reg))
> > >    			goto cleanup;
> > > +
> > > +		ssc_clk_index = 4;
> > > +	} else {
> > > +		ssc_clk_index = 3;
> > > +	}
> > > +
> > > +	if (dd->ssc_deltam_int_mask && dd->ssc_deltam_frac_mask &&
> > > +	    dd->ssc_modfreq_mant_mask && dd->ssc_modfreq_exp_mask) {
> > > +		if (ti_clk_get_reg_addr(node, ssc_clk_index++,
> > > +					&dd->ssc_deltam_reg))
> > > +			goto cleanup;
> > > +
> > > +		if (ti_clk_get_reg_addr(node, ssc_clk_index++,
> > > +					&dd->ssc_modfreq_reg))
> > > +			goto cleanup;
> > > +
> > > +		of_property_read_u32(node, "ti,ssc-modfreq", &dd->ssc_modfreq);
> > > +		of_property_read_u32(node, "ti,ssc-deltam", &dd->ssc_deltam);
> > > +		if (of_property_read_bool(node, "ti,ssc-downspread"))
> > > +			dd->ssc_downspread = 1;
> >
> > New bindings.
>
> I added the bindings documentation in another patch of the series.

oh. sorry I've not received it for some reasons :(

--
Best regards,
grygorii