EIM performance difference between IMX6Quad and IMX6QuadPlus

[udayakumar]

Hello,

We have accessed EIM write and read in u-boot in IMX6Quad processor, where we have got a turn around time of 230ns.

The scope image for configuration data bus Data 0-16 is

EIM_CS0GCR1 = 0x00010081
EIM_CS0GCR2 = 0x00000000
EIM_CS0RCR1 = 0x02000000
EIM_CS0RCR2 = 0x00000000
EIM_CS0WCR1 = 0x02000000
EIM_CS0WCR2 = 0x00000000

Where the turn around time is not in range as we expected, so we opted for IMX6QuadPlus processor where internal bus frequency is higher and faster. But the turn around time here is 330ns,100ns more than the IMX6Quad processor.

The scope image for configuration data bus Data 16-31 in IMX6QP SabreSD board is

EIM_CS0GCR1 = 0x00020081
EIM_CS0GCR2 = 0x00000000
EIM_CS0RCR1 = 0x02000000
EIM_CS0RCR2 = 0x00000000
EIM_CS0WCR1 = 0x02000000
EIM_CS0WCR2 = 0x00000000

Why performance drop from IMX6Q to IMX6QP processor ?

Any bus registers configurations need to be changed for better performance to achieve turn around time less than 100ns?

thanks ,

uday

[udayakumar]

Hi Igor

I could not find EIM apb_slave index in imx6 reference manaul. Could you please share me the apb_slave index of EIM and its QoS default value.

thanks,

uday

[igorpadykov]

seems it is GPV_3 index=82, default value=2 as for

other peripherals.

~igor

[udayakumar]

Hi Igor,

I try to write 0x03 and read back value is 0.

In data sheet its given as reserved ,have any idea to write and read and need to take care anything?

thanks,

uday

[udayakumar]

Hi Igor

For the

Write QoS: "0x00C4_9104"   what is the minmum and maximum value can be written?

thanks

uday

[igorpadykov]

Hi uday

it is 4 bit wide and description can be found in arm NIC-301 Technical Reference Manual

http://infocenter.arm.com/help/topic/com.arm.doc.ddi0397i/DDI0397I_corelink_network_interconnect_nic... 

Best regards
igor

[igorpadykov]

Hi uday

delays are introduced mostly by bus arbiters nic301 and since i.MX6QuadPlus

has more complex architecture, it may have more delays. Difference is described in

EB810 i.MX6Dual/6Quad and i.MX6DualPlus/6QuadPlus Applications Processor Comparison

http://cache.nxp.com/docs/en/engineering-bulletin/EB810.pdf 

In general one can try to tweak QoS (EIM connected to GPV_3) usingsect.47.3.3.1 NIC-301 QoS

Reference Manual.

Best regards
igor
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