ECSPI5 Rx Problem

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ECSPI5 Rx Problem

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andrelabelle111
Contributor I

Hi,

I have a  RTC SPI device (PCF2123) connected to the i.MX6Q ECSPI5 peripheral. I'm using a GPIO to control the chip select.

A logic analyzer attached to the SCK,MOSI,MISO and CS pins show the external signals are good. I can read the current time and see the time increment on MISO.

The problem is the data received from the peripheral is always zero, even though I see the correct data on MISO.

I'm using:

u-boot: git://source.codeaurora.org/external/imx/uboot-imx.git imx_v2018.03_4.14.62_1.0.0_beta

linux: source.codeaurora.org/external/imx/linux-imx/ imx_4.14.62_1.0.0_beta

Here are some clues I have gathered:

-no problem if I downgrade to an older boundary u-boot (around 2014-12)

-if I put the peripheral in loopback mode, the tx data is received correctly (no longer rx all zeroes)

-same issue when using either the pcf2123 driver or the spidev driver

-the other ECSPIx peripherals are working fine

I tried comparing memory spaces (using memtool) between the working version (using the old u-boot) and non-working version.

ECSPI5 address space matches

IOMUX address had minor changes, new u-boot sets the drive strength to 48ohm instead of 40ohm on some pins

CCM address space matches

CCM analog, difference in CCM_ANALOG_PLL_ARM/CCM_ANALOG_PFD_528n

Thank you for reading this. Any hints or suggestions would be greatly appreciated.

Andre

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andrelabelle111
Contributor I

Hi Igor,

Thanks for the suggestion. I figured out why it wasn't working. Our hardware has a buffer between the RTC chip and the I.MX6. The i.MX6 GPIO that controls the output enable for that buffer is gets set to an input at some point during boot. I'm still investigating.

Thanks for your help.

Andre

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Andre

may be recommended to try latest nxp L4.14.78 :

uboot-imx - i.MX U-Boot 

linux-imx - i.MX Linux kernel 

Best regards
igor
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