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About eDMA channel 0

Question asked by Makoto Katsukura on Mar 20, 2014
Latest reply on Apr 1, 2014 by Timesys Support

Dear Forum members,

 

Is there any special meaning for eDMA channel 0?

We are using Timesys Linux and in their UART driver (mvf.c), following codes imply eDMA channel 0 has special meaning.

 

(linux3.0/drivers/tty/serial/mvf.c

static void imx_shutdown(struct uart_port *port)
{
    struct imx_port *sport = (struct imx_port *)port;
    unsigned char temp;
    unsigned long flags;


    if (sport->enable_dma) {
        /* We have to wait for the DMA to finish. */
        if (sport->dma_tx_ch) {
            mcf_edma_stop_transfer(sport->dma_tx_ch);
            mcf_edma_free_channel(sport->dma_tx_ch, sport);
            sport->dma_tx_ch = 0;
        }
    }

 

Line 10 to 14 is not executed when UART uses DMA channel 0 (Because, sport->dma_tx_ch is 0 ).

We think those are just a software bug, but we want to confirm that eDMA channel 0 has special meaning or not.

 

Thank you,

Makoto Katsukura

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