AM2634: MCSPI driver not stable at certain clock configuration

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/* This example demonstrates the McSPI RX and TX operation configured
 * in DMA mode of operation.
 *
 * This example sends a known data in the TX mode of length APP_MCSPI_MSGSIZE
 * and then receives the same in RX mode. Internal pad level loopback mode
 * is enabled to receive data.
 * To enable internal pad level loopback mode, D0 pin is configured to both
 * TX Enable as well as RX input pin in the SYSCFG.
 *
 * When transfer is completed, TX and RX buffer data are compared.
 * If data is matched, test result is passed otherwise failed.
 */

#include <kernel/dpl/CacheP.h>
#include <kernel/dpl/DebugP.h>
#include "ti_drivers_config.h"
#include "ti_drivers_open_close.h"
#include "ti_board_open_close.h"

#define APP_MCSPI_TRANSFER_LOOPCOUNT    10
#define APP_MCSPI_MSGSIZE               4

uint32_t gMcspiTxBuffer[APP_MCSPI_MSGSIZE] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));
uint32_t gMcspiRxBuffer[APP_MCSPI_MSGSIZE] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));

void *mcspi_loopback_dma_main(void *args)
{
    int32_t             status = SystemP_SUCCESS;
    uint32_t            i, j;
    int32_t             transferOK;
    MCSPI_Transaction   spiTransaction;
    uint64_t            startTimeInUSec, elapsedTimeInUsecs;

    Drivers_open();
    Board_driversOpen();

    DebugP_log("[MCSPI] Loopback example DMA mode started ...\r\n");

    /* Memfill buffers */
    for(i = 0U; i < APP_MCSPI_MSGSIZE; i++)
    {
        gMcspiTxBuffer[i] = i + 1U;
        gMcspiRxBuffer[i] = 0U;
    }

    /* Writeback buffer */
    CacheP_wb(&gMcspiTxBuffer[0U], sizeof(gMcspiTxBuffer), CacheP_TYPE_ALLD);
    CacheP_wb(&gMcspiRxBuffer[0U], sizeof(gMcspiRxBuffer), CacheP_TYPE_ALLD);

    /* Initiate transfer */
    MCSPI_Transaction_init(&spiTransaction);
    spiTransaction.channel  = gConfigMcspi0ChCfg[0].chNum;
    spiTransaction.dataSize = 32U;
    spiTransaction.csDisable = TRUE;
    spiTransaction.count    = APP_MCSPI_MSGSIZE;
    spiTransaction.txBuf    = (void *)gMcspiTxBuffer;
    spiTransaction.rxBuf    = (void *)gMcspiRxBuffer;
    spiTransaction.args     = NULL;
    startTimeInUSec = ClockP_getTimeUsec();
    for(j = 0U; j < APP_MCSPI_TRANSFER_LOOPCOUNT; j++)
    {
    transferOK = MCSPI_transfer(gMcspiHandle[CONFIG_MCSPI0], &spiTransaction);
    }
    elapsedTimeInUsecs = ClockP_getTimeUsec() - startTimeInUSec;

    DebugP_log("----------------------------------------------------------\r\n");
    DebugP_log("McSPI Clock %d Hz\r\n", gConfigMcspi0ChCfg[0U].bitRate);
    DebugP_log("----------------------------------------------------------\r\n");
    DebugP_log("Data Width \tData Length \tTransfer Time (micro sec)\r\n");
    DebugP_log("%u\t\t%u\t\t%5.2f\r\n", spiTransaction.dataSize, APP_MCSPI_MSGSIZE,
                        (float)elapsedTimeInUsecs / APP_MCSPI_TRANSFER_LOOPCOUNT);
    DebugP_log("----------------------------------------------------------\r\n\n");

    if((SystemP_SUCCESS != transferOK) ||
       (MCSPI_TRANSFER_COMPLETED != spiTransaction.status))
    {
        DebugP_assert(FALSE); /* MCSPI transfer failed!! */
    }
    else
    {

        /* Invalidate cache */
        CacheP_inv(&gMcspiRxBuffer[0U], sizeof(gMcspiRxBuffer), CacheP_TYPE_ALLD);
        /* Compare data */
        for(i = 0U; i < APP_MCSPI_MSGSIZE; i++)
        {
            if(gMcspiTxBuffer[i] != gMcspiRxBuffer[i])
            {
                status = SystemP_FAILURE;   /* Data mismatch */
                DebugP_log("Data Mismatch at offset %d\r\n", i);
                break;
            }
        }
    }

    if(SystemP_SUCCESS == status)
    {
        DebugP_log("All tests have passed!!\r\n");
    }
    else
    {
        DebugP_log("Some tests have failed!!\r\n");
    }

    Board_driversClose();
    Drivers_close();

    return NULL;
}