2010-05-05 11:58:32     BF537 spi_sync returns error

2010-05-05 11:58:32     BF537 spi_sync returns error

Adam Rosenberg (UNITED STATES)

Message: 89155   

I am trying to write a sound driver that can communicate with a Cirrus Logic CS42448 using the BF537 SPI driver.

The value of result at the end of the following code is -5.  I do not know how to debug kernel modules using a debugger so I have been trying to trace this manually.  From what I can tell, -5 is actually -EIO which is set as the message status in bfin_spi_pump_transfers in spi_bfin5xx.c

What are the possible causes of this error?

-- code --

    unsigned char msg[3];

    int result = 0;

    struct spi_transfer tw = {

            .tx_buf = &msg,

            .len = 3,

        };

    struct spi_message m;

    msg[0] = (CS42448_CHIP_ADDR | CS42448_CHIP_WRITE);

    msg[1] = (CS42448_REG_POWER_CONTROL & CS42448_MAP_MASK);

    msg[2] = 0x01;

  

    spi_message_init(&m);

    spi_message_add_tail(&tw, &m);

    result = spi_sync(me->spi, &m);

-- end code --

Thank you,

Adam

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2010-05-05 15:06:54     Re: BF537 spi_sync returns error

Mike Frysinger (UNITED STATES)

Message: 89160   

all negative values are errno values, so look it up in the errno headers.  -5 is -EIO.

as for where the error is coming from, enable debugging in the relevant drivers (#define DEBUG) and look at where it's coming from.

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2010-05-06 09:26:53     Re: BF537 spi_sync returns error

Adam Rosenberg (UNITED STATES)

Message: 89180   

Mike,

Thank you for your quick response. Here is the output from the debug messages:

bfin-spi bfin-spi.0: restoring spi ctl state

bfin-spi bfin-spi.0: got a message to pump, state is set to: baud 20, flag 0x20, ctl 0x1000

bfin-spi bfin-spi.0: the first transfer len is 3

bfin-spi bfin-spi.0: tx_buf is 03bd8308, tx_end is 03bd830b

bfin-spi bfin-spi.0: transfer: drv_data->write is 00090870, chip->write is 00090870, null_wr is 000905f8

bfin-spi bfin-spi.0: now pumping a transfer: width is 1, len is 3

bfin-spi bfin-spi.0: doing IO transfer

bfin-spi bfin-spi.0: IO write: cr is 0x5100

bfin-spi bfin-spi.0: IO write error!

bfin-spi bfin-spi.0: transfer: we've hit an error

What are the possible causes of this error?

Thank you,

Adam

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2010-05-06 09:42:53     Re: BF537 spi_sync returns error

Michael Hennerich (GERMANY)

Message: 89181    In your platform board file - could it be that you set bfin5xx_spi_chip.bits_per_word = 16 ?

This might explain the error for the odd transfer count.

-Michael

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2010-05-06 10:19:14     Re: BF537 spi_sync returns error

Adam Rosenberg (UNITED STATES)

Message: 89184   

Mike,

I looked through the area of the code that caused the "bfin-spi bfin-spi.0: IO write error!" and took a guess that it doesn't like writing only 3 bytes.  I padded my write with a zero at the end and sure enough, it worked.  I do not yet know if that extra byte is going to cause problems when I try to communicate with the CS42448 but at least I am one step closer.  I will keep you posted if anything changes.

Thanks,

Adam

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2010-05-06 10:21:21     Re: BF537 spi_sync returns error

Adam Rosenberg (UNITED STATES)

Message: 89185   

You are correct, I didn't change bits per word to 8!  Thanks I will try that now.

-Adam