Re: adding SPI port on i.MX27 board

[Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>]

On 14:41 Fri 17 Aug     , Vanalme Filip wrote:
>    Hi,
> 
>     
> 
>    Currently, CSPI2 of the i.MX27 is used to communicate with its companion
>    chip (MC13783). This works fine. The SPI parts of the board file look like
>    :
> 
>     
> 
>    static int imx27_interaxio_spi1_cs[] = {GPIO_PORTD + 21};
> 
>    static struct spi_imx_master imx27_interaxio_spi_1_data = {
> 
>        .chipselect = imx27_interaxio_spi1_cs,
> 
>        .num_chipselect = ARRAY_SIZE(imx27_interaxio_spi1_cs),
> 
>    };
> 
>     
> 
>    static struct spi_board_info imx27_interaxio_spi_board_info[] = {
> 
>        {
> 
>          .name = "mc13783",
> 
>          .max_speed_hz = 3000000,
> 
>          .bus_num = 0,
> 
>          .chip_select = 0, /* offset in the chip select array */
> 
>        },
> 
>    };
> 
>     
> 
>    [...]
> 
>     
> 
>    static int imx27_interaxio_devices_init(void)
> 
>    {
> 
>      [...]
> 
>      /* PMIC support */
> 
>      spi_register_board_info(imx27_interaxio_spi_board_info,
>    ARRAY_SIZE(imx27_interaxio_spi_board_info));
> 
>      imx27_add_spi1(&imx27_interaxio_spi_1_data);
> 
>    [...]
> 
>     
> 
>     
> 
>    Now, I would like to add another SPI port of the i.MX27, CSPI1, to control
>    an LCD. To do that, I taught I had to change the board file like this :
> 
>     
> 
>    static int imx27_interaxio_spi1_cs[] = {GPIO_PORTD + 21};
> 
>    static int imx27_interaxio_spi0_cs[] = {GPIO_PORTD + 28};
> 
>    static struct spi_imx_master imx27_interaxio_spi_1_data = {
> 
>        .chipselect = imx27_interaxio_spi1_cs,
> 
>        .num_chipselect = ARRAY_SIZE(imx27_interaxio_spi1_cs),
> 
>    };
> 
>    static struct spi_imx_master imx27_interaxio_spi_0_data = {
> 
>        .chipselect = imx27_interaxio_spi0_cs,
> 
>        .num_chipselect = ARRAY_SIZE(imx27_interaxio_spi0_cs),
> 
>    };
> 
>    static struct spi_board_info imx27_interaxio_spi_board_info[] = {
> 
>        {
> 
>          .name = "mc13783",
> 
>          .max_speed_hz = 3000000,
> 
>          .bus_num = 0,
> 
>          .chip_select = 0,
> 
>        },
> 
>        {
> 
>            .name = "LCD",
> 
>            .max_speed_hz = 2000000,
> 
>            .bus_num = 1,
> 
>            .chip_select = 0, 
> 
>        },
> 
>    };
> 
>     
> 
>    [...]
> 
>     
> 
>    static int imx27_interaxio_devices_init(void)
> 
>    {
> 
>      [...]
> 
>      /* PMIC support */
> 
>      spi_register_board_info(imx27_interaxio_spi_board_info,
>    ARRAY_SIZE(imx27_interaxio_spi_board_info));
> 
>      imx27_add_spi1(&imx27_interaxio_spi_1_data);
> 
>      imx27_add_spi0(&imx27_interaxio_spi_0_data);
> 
>    [...]
> 
>     
> 
>     
> 
>    However, I'm not sure I'm doing it right. E.g. for the bus_num element. As
>    it is another `master', I guess it should get another bus number. However,
>    when digging a little in the code, in imx_spi_probe (imx_spi.c), bus_num
>    of `master' is never initialized, so always 0. A little further, when
>    scanning for board info (scan_boardinfo in spi.c), bus_num of chip is
>    compared to bus_num of master, which is always 0. For the existing
>    implementation this was not a problem as the bus_num in the board info
>    struct was also 0. For the added bus, the bus_num is 1, so the compare
>    will validate to false and the device will not be created...
> 
>    This is how I'm think it's working. Am I correct ?
> 
>    Am I doing something wrong ? Should I also use bus_num 0 for my additional
>    SPI instead of 1 ?
I get the same issue on at91 recently I send a patch to detect this issue

here you have 2 choice use the dynamic bus num allocation or manual but all
the bus must have a different bus_num

Best Regards,
J.

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