trying to get boot-console working on Gumstix Overo

[erazor83]

Hi there,

I just hope thats the right place to ask.

Currently I'm trying to get a boot-console working with fbtft and fbcon.

Compiling fbtft as a module, loading it after boot and playing with fbv works nicely. However, I tried to compile everything into the kernel and am not getting an fb-device anymore.

My syslog looks like this:

[    0.228363] fbtft_device:  SPI devices registered:
[    0.228393] fbtft_device:  'fb' Platform devices registered:
[    0.228607] fbtft_device:  GPIOS used by 'sainsmart18':
[    0.228607] fbtft_device:    'reset' = GPIO17
[    0.228637] fbtft_device:    'dc' = GPIO19
...
[    0.410461] vads7846: 3300 mV 
...
[    1.776519] omap2_mcspi omap2_mcspi.1: can't create new device for fb_st7735r
[    1.776519] omap2_mcspi omap2_mcspi.1: can't create new device for fb_st7735r
[    9.430694] ads7846 spi1.0: touchscreen, irq 210
[    9.438934] ads7846 spi1.0: no device detected, test read result was 0x00000000

I've given module-parameters via kernel command-line:

console=ttyO2,115200 mpurate=500 vram=12M root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait i2c_bus=3,100 fbtft_device.name=sainsmart18 fbtft_device.busnum=1 fbtft_device.gpios=reset:17,dc:19

So, since mcspi.1 complains it seems like fbtft_device got the parameters correctly.

I'm a bit stuck on how to continue and debug this issue, maybe the SPI is not ready and the probing of fbtft_device does not work?

Thanks for any hints.

[notro]

Since you don't specify which chipselect to use for fbtft_device, the default will be 0. In other words, with busnum=1 it will be spi1.0. But this is what ads7846 is using... Are they trying to use the same chipselect?

[erazor83]

I removed the ads7846 which was compiled as a module but still: [ 1.776519] omap2_mcspi omap2_mcspi.1: can't create new device for fb_st7735r

I started to add some lines to the board file which now looks like this

...
    {
        .modalias = "fb_st7735r",
        .max_speed_hz = 32000000,
        .bus_num = 1,
        .chip_select = 0,
        .mode = SPI_MODE_0,
        .platform_data = &(struct fbtft_platform_data) {
            .gpios = (const struct fbtft_gpio []) {
                    { "reset", 17 },
                    { "dc", 19 },
             },
        }
    },
#endif
    {
        .modalias       = "spidev",
        .bus_num        = 1,
        .chip_select        = 0,
        .max_speed_hz       = 48000000,
        .mode           = SPI_MODE_0,
    },
#endif
...

But except the display went black and I got a device listed in /proc/fb nothing else happens.

It's probably some missing parameters or wrong module name.

Also the driver don't know about the display type. How can I add this to the board file?

[notro]

I removed the ads7846 which was compiled as a module but still

I'm talking devices here, not modules/drivers. Removing the module wouldn't help on a device conflict.

The board file looks fine to me. If the display goes black, it has been initialized. Meaning the driver has been probed. You should have a line in your kernel log when the driver is loaded, like this (this is for a different display):

graphics fb1: fb_ili9341 frame buffer, 320x240, 150 KiB video memory, 16 KiB buffer memory, fps=20, spi0.0 at 32 MHz

And you should get /dev/fbX

Do you have more framebuffers in your system (/dev/fb0, /dev/fb1) ?

[erazor83]

no other framebuffers

[    0.227203] fbtft_device:  SPI devices registered:
[    0.227233] fbtft_device:  'fb' Platform devices registered:
[    0.227447] fbtft_device:  GPIOS used by 'sainsmart18':
[    0.227447] fbtft_device:    'reset' = GPIO17
[    0.227478] fbtft_device:    'dc' = GPIO19
[    0.281860] bio: create slab  at 0
[    1.734985] fb_st7735r spi1.0: no default functions for regwidth=8 and buswidth=0
[    2.839538] Console: switching to colour frame buffer device 16x20
[    2.846984] graphics fb0: fb_st7735r frame buffer, 128x160, 40 KiB video memory, 4 KiB buffer memory, fps=21, spi1.0 at 32 MHz
[    2.859436] omap2_mcspi omap2_mcspi.1: chipselect 0 already in use
[    2.866210] omap-dma-engine omap-dma-engine: freeing channel for 36
[    2.872955] omap-dma-engine omap-dma-engine: freeing channel for 35
[    2.880096] omap2_mcspi omap2_mcspi.1: can't create new device for spidev
[    2.887451] omap-dma-engine omap-dma-engine: allocating channel for 38
[    2.894409] omap-dma-engine omap-dma-engine: allocating channel for 37
[    2.906616] omap2_mcspi omap2_mcspi.1: chipselect 0 already in use
[    2.913330] omap2_mcspi omap2_mcspi.1: can't create new device for fb_st7735r
[    2.922637] Unable to handle kernel NULL pointer dereference at virtual address 00000000

So how does he know about sainsmart18? Do I still have to use the command line args for the kernel?

[notro]

You need to specify buswidth as well in the board file. That's why you get that NULL pointer exception. From fbtft_device:

        .name = "sainsmart18",
        .spi = &(struct spi_board_info) {
            .modalias = "fb_st7735r",
            .max_speed_hz = 32000000,
            .mode = SPI_MODE_0,
            .platform_data = &(struct fbtft_platform_data) {
                .display = {
                    .buswidth = 8,
                },
                .gpios = (const struct fbtft_gpio []) {
                    { "reset", 25 },
                    { "dc", 24 },
                    {},
                },
            }
        }

You can drop the fbtft_device parameters from the kernel command line when you specify the SPI device in the board file. That's why you get some of the errors at least. If fbtft_device doesn't find a 'name' argument it just does nothing.

[erazor83]

is this part of a platform_device ? I'm wondering because of .spi and .name. I only added some lines to the spi part of the board:

static struct spi_board_info overo_spi_board_info[] __initdata = {
#if !defined(CONFIG_TOUCHSCREEN_ADS7846) && \
    !defined(CONFIG_TOUCHSCREEN_ADS7846_MODULE) && \
    (defined(CONFIG_SPI_SPIDEV) || defined(CONFIG_SPI_SPIDEV_MODULE))
#if defined(CONFIG_FB_TFT_ST7735R)
    {
        .modalias = "fb_st7735r",
        .max_speed_hz = 32000000,
        .bus_num = 1,
        .chip_select = 0,
        .mode = SPI_MODE_0,
        .platform_data = &(struct fbtft_platform_data) {
            .display = {
                    .buswidth = 8,
            },
            .gpios = (const struct fbtft_gpio []) {
                    { "reset", 17 },
                    { "dc", 19 },
                    {},
             },
        }
    },
#endif
    {
        .modalias       = "spidev",
        .bus_num        = 1,
        .chip_select        = 0,
        .max_speed_hz       = 48000000,
        .mode           = SPI_MODE_0,
    },
#endif
...

[notro]

is this part of a platform_device

No. When the SPI master is registered, all the spi_board_info's that has been added, will be registered as spi_device's on that SPI master. It happens here: http://lxr.free-electrons.com/source/drivers/spi/spi.c#L1383

[erazor83]

Ok, removed the kernel params and added .buswidth. Still kernel errors:

Overo ~ # dmesg | grep fb
[    2.806762] graphics fb0: fb_st7735r frame buffer, 128x160, 40 KiB video memory, 4 KiB buffer memory, fps=21, spi1.0 at 32 MHz
Overo ~ # dmesg | grep spi
[    2.806762] graphics fb0: fb_st7735r frame buffer, 128x160, 40 KiB video memory, 4 KiB buffer memory, fps=21, spi1.0 at 32 MHz
[    2.819244] omap2_mcspi omap2_mcspi.1: chipselect 0 already in use
[    2.839477] omap2_mcspi omap2_mcspi.1: can't create new device for spidev
[    2.901580] PC is at omap2_mcspi_transfer_one_message+0x570/0xc68
[    2.908020] LR is at omap2_mcspi_transfer_one_message+0x3d8/0xc68
[    2.959869] Process spi1 (pid: 554, stack limit = 0xdfadc2f8)
[    3.048645] [] (omap2_mcspi_transfer_one_message+0x570/0xc68) from [] (spi_pump_messages+0x118/0x13c)
[    3.060302] [] (spi_pump_messages+0x118/0x13c) from [] (kthread_worker_fn+0xd8/0x130)

I posted my board-overo.c here: http://pastebin.com/s3Vz9HbD

[notro]

[ 2.819244] omap2_mcspi omap2_mcspi.1: chipselect 0 already in use [ 2.839477] omap2_mcspi omap2_mcspi.1: can't create new device for spidev

Because you have this

        {
                .modalias               = "spidev",
                .bus_num                = 1,
                .chip_select            = 0,
                .max_speed_hz           = 48000000,
                .mode                   = SPI_MODE_0,
        },

The same bus_num and chip_select as fb_st7735r

Do you have console output now?

[erazor83]

Works perfectly thanks a lot notro!

[notro]

You're welcome. Please close the issue if your done.