confuse about QuadSPI ref clk

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

confuse about QuadSPI ref clk

489 Views
changbaoma
Contributor III

Hi, all

     

   I notice there is a figure about QuadSPI, and it specify ref use "cluster1 clk". see below.

   6.png

But at ls1021a dts, qspi clocks ref to platform_clk's "platform-clk-div2", and  platform_clk ref to fixed-clock "sysclk" , as i know the sysclk is fixup to 100MHz at u-boot phare.

7.png

And there is another about QuadSPI, Is it says QuadSPI clk  can be ref to "platform clk" or "cluster1 clk"?  and how can we choice those ref clk?

5.png

and why ls1021a dts choice sysclk(100MHz) as qspi's the ref clk ? 

(actually i find the QSPI_CLK is depend  on CPU clock only, when i change the cpu freq by /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor at run time )

 

Labels (1)
0 Kudos
1 Reply

376 Views
r8070z
NXP Employee
NXP Employee

According to the LS1021A manual in the RCW phase QSPI gets sysclk and in the PBI Phase/Boot Phase it gets the core clock1. See 29.1.5 LS1021A QuadSPI module special consideration (LS1021ARM rev.3). It seems manuals Figure 4-8. “Clock subsystem block diagram - IP modules” reflects that.

If we look at

 platform_clk: pll@c00 {

                                                            compatible = "fsl,core-pll-clock";

                                                            #clock-cells = <1>;

                                                            reg = <0xc00>;

                                                            clocks = <&sysclk>;

                                                            clock-output-names = "platform-clk", "platform-clk-div2";

we can find that "platform_clk" label actually points to the core pll clock. It also can confuse me. For device tree we should refer to corresponding binding documentation described which properties are accepted and its values. I have not checked  but can suppose  that "platform-clk", "platform-clk-div2"; corresponds to the Figure 4-7. “Clock subsystem block diagram - cluster group A” where C1_PLL_SEL selects direct and ½ options.

0 Kudos