imx6qp ECSPI slave mode TX data missing

sijilcv — Tue, 26 Apr 2016 06:45:30 GMT

We have developed a custom ECSPI slave driver for iMX6 and tested it on saber AI development board with imx6qp processor (MCIMX6QPAICPU3.)

The ECSPI_1 lines of the development board is connected to another microcontroller for testing.

Following are our observations.

The Reception (MOSI) on imx6 side was working perfectly. but on the transmission side (MISO) we observed that some bytes are missing in TX data.

Could you please help us to resolve this issue.

Another strange thing is that the same code works perfectly in a imx6 saber lite evaluation board, both Tx and Rx data is perfect.

#define SPI_LENGTH 64

struct spi_transfer

{

uint8_t rx[SPI_LENGTH];

uint8_t tx[SPI_LENGTH];

};

typedef struct __spi_dev{

struct spi_transfer spi_xfer;

int irq;

void __iomem *base;

struct clk *clk_per;

struct clk *clk_ipg;

unsigned long spi_clk;

unsigned int spi_bus_clk;

struct completion xfer_done;

}spi_dev_t;

spi_dev_t * p_spi_dev = NULL;

Reg Configuration:

static int setup_spi_slave(spi_dev_t *spi_imx)

{

writel(0x00000000, p_spi_dev->base + MX51_ECSPI_CTRL); /* Reset ecspi*/

writel(0x00700001, p_spi_dev->base + MX51_ECSPI_CTRL); /* Burst length to 1 byte */

writel(0x00000011, p_spi_dev->base + MX51_ECSPI_CONFIG); /* Set PHA and POL*/

writel(0x003f0000, p_spi_dev->base + MX51_ECSPI_DMA); /* Set threshold to 63 bytes */

writel(0x00000010, p_spi_dev->base + MX51_ECSPI_INT); /* Set threshold interrupt */

return 0;

}

ISR code

static irqreturn_t imx6_spi_slave_isr(int irq, void *dev_id)

{

static unsigned int count = 0;

while (rx_available(p_spi_dev))

{

p_spi_dev->spi_xfer.rx[count] = (uint8_t)readl(p_spi_dev->base + MXC_CSPIRXDATA);

writel(p_spi_dev->spi_xfer.tx[count],p_spi_dev->base + MXC_CSPITXDATA);

count++;

}

count = 0;

/*Clear TX buff*/

memset(&p_spi_dev->spi_xfer.tx,0,SPI_LENGTH);

complete(&p_spi_dev->xfer_done);

return IRQ_HANDLED;

}

The buffer is filled with following data.

static void fill_tx_buff(void)

{

snprintf(p_spi_dev->spi_xfer.tx,64,"%s","This code is to test ECSPI communication between two micro \r\n");

}

The output is as follows.

[0] 'T'

[1] 'h'

[2] 'i'

[3] 's'

[4] ' '

[5] 'o' /* c is missing */

[6] 'd'

[7] 'e'

[8] ' '

[9] 'i'

[10] 's'

[11] ' '

[12] 't'

[13] ' ' /* o missing */

[14] 't'

[15] 's' /* e missing */

[16] 't'

[17] ' '

[18] 'E'

[19] 'C'

[20] 'S'

[21] 'P'

[22] 'I'

[23] ' '

[24] 'c'

[25] 'o'

[26] 'm'

[27] 'm'

[28] 'u'

[29] 'n'

[30] 'i'

[31] 'c'

[32] 'a'

[33] 't'

[34] 'i'

[35] 'o'

[36] 'n'

[37] ' '

[38] 'b'

[39] 't' /* e missing */

[40] 'w'

[41] 'e'

[42] 'e'

[43] 'n'

[44] ' '

[45] 't'

[46] 'w'

[47] 'o'

[48] ' '

[49] 'm'

[50] 'i'

[51] 'c'

[52] 'r'

[53] 'o'

[54] ' '

[55] ' '

[56] '\r

[57] '\n

[58] ' '

Re: imx6qp ECSPI slave mode TX data missing

gusarambula — Tue, 03 May 2016 19:33:24 GMT

Hello Sijil CV,

This seems to be a hardware problem rather than a software problem, since it works correctly with the i.MX6 Sabrelite board.

I would recommend checking how the ESCPI lines are connected since it’s possible that the voltages are falling due to unwanted loads on the line.

Regards,

Re: imx6qp ECSPI slave mode TX data missing

gary_bisson — Wed, 04 May 2016 10:10:07 GMT

Hi,

Would you mind sharing this slave driver source code? Or does it include proprietary sections you can't share?

Regards,

Gary

Re: imx6qp ECSPI slave mode TX data missing

sijilcv — Wed, 04 May 2016 15:48:38 GMT

Thanks gusarambula yes it was a hardware issue.

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imx6qp ECSPI slave mode TX data missing

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