Can ECSPI2 master connect to total 4 slave devices?

[joseph_chen]

Hi,

For IMX8MQ, our designed board's ECSPI2 connects to 2 SPI slave devices already.  There is a need to have the master to connects to 2 more.  So can the master connects to and control total 4 slave devices?

[igorpadykov]

HI Joe

yes it is possible configuring dts "cs-gpios" properly :

fsl-imx-cspi.txt\spi\bindings\devicetree\Documentation - linux-imx - i.MX Linux kernel 

Best regards
igor
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[joseph_chen]

Hi Igor,

Thanks for you great help. Following the doc, I'm able to add an extra "cs-gpios" for a third SPI-slave device to the existing ECSPI2.

However, immediately after the adding, Linux kernel starts giving errors like:

[ 1.130032] spi_imx 30820000.ecspi: dma setup error -19, use pio
[ 1.136699] spi_imx 30820000.ecspi: probed
[ 1.141145] spi_imx 30830000.ecspi: dma setup error -19, use pio
[ 1.147706] spi_imx 30830000.ecspi: probed

FYI, I tried but I'm unable to find a related location in the device tree DTS file to add any additional DMA to the third SPI-slave device.

Any recommendations to how to fix this? 

-- Joe

[igorpadykov]

HI Joe

one can try to use pio option removing dma entries in dts.

Best regards
igor