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How to adjust parameters of PCIe_PHY by changing the IOMUXC_GPR8 register ??

Question asked by Peter Amond on Nov 27, 2018
Latest reply on Dec 3, 2018 by igorpadykov

Hi All


I already read AN4784 document, but it did not help us a lot since I don't have the measure equipment to process the Sig test. I couldn't find any explanation on how to configure IOMUXC_GPR8 fields without following AN4784 procedure, which is very cost effective when I does't have the measure equipment like 20GHz oscilloscope.


1) Can you explain me how each field of IOMUXC_GPR8 modifies PHY Tx timings/levels ?


As an example what are the values I can use for following ? Instead to using 127 for bit 25 what we can use as other values ? Can you tell me the values I can test with for PCIE GEN 1 by changing DEEMPH_GEN1, TX_SWING_FUL and TX_SWING_LOW. 


imx_pcie_clrset(IOMUXC_GPR8_TX_DEEMPH_GEN1, 0 << 0, IOMUXC_GPR8);
imx_pcie_clrset(IOMUXC_GPR8_TX_DEEMPH_GEN2_3P5DB, 0 << 6, IOMUXC_GPR8);
imx_pcie_clrset(IOMUXC_GPR8_TX_DEEMPH_GEN2_6DB, 20 << 12, IOMUXC_GPR8);
imx_pcie_clrset(IOMUXC_GPR8_TX_SWING_FULL, 127 << 18, IOMUXC_GPR8);
imx_pcie_clrset(IOMUXC_GPR8_TX_SWING_LOW, 127 << 25, IOMUXC_GPR8);


2) Let's say we are using Sig test then how we can use test measurements to change this 127 value ? How you get this value with sig tool measurements ?



3) If I'm using /unit_tests/memtool -32 0x020e0020= FFFD4000 memtool what values I can try instead of FFFD4000 ?


Thank you for your support.