2009-06-08 09:20:45 general driver question

Nikolay Chokoev (IRELAND)

Message: 75335

Hi,

I have a LCD driver that needs to access I2C, but the I2C driver is attached after the LCD driver is finished. It seems that the i2c_add_driver() is asynchronous.

static int __devinit bfin_ra158z_driver_init(void)

{

printk(KERN_INFO DRIVER_NAME ": bfin_ra158z_driver_init.\n");

if (i2c_add_driver(&eep_driver)) {

printk(KERN_ERR DRIVER_NAME ": I2C Driver Initialisation failed\n");

}

return platform_driver_register(&bfin_ra158z_driver);

}

bfin-ra158z: bfin_ra158z_driver_init.

bfin-ra158z: FrameBuffer initializing...

bfin-ra158z: get_configuration

dma_alloc_init: dma_page @ 0x01edd000 - 256 pages at 0x01f00000

Console: switching to colour frame buffer device 100x30

Serial: Blackfin serial driver

bfin-uart.1: ttyBF0 at MMIO 0xffc00400 (irq = 29) is a BFIN-UART

brd: module loaded

loop: module loaded

bfin-spi bfin-spi.0: No DMA channel specified

bfin-spi: probe of bfin-spi.0 failed with error -2

bfin-ra158z: eep_attach

bfin-ra158z: eep_probe

bfin-ra158z: eep_probe OK!

Regards,

Nikolay

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2009-06-08 09:43:53 Re: general driver question

Mike Frysinger (UNITED STATES)

Message: 75336

adding the driver only registers its availability. there is no guarantee as to when exactly in the boot process the i2c client will be discovered and the registered driver executed.

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2009-06-08 09:52:40 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75337

...how to proceed? What's the solution?

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2009-06-08 10:03:20 Re: general driver question

Mike Frysinger (UNITED STATES)

Message: 75338

i dont see a problem. why do you need the i2c available at time of the framebuffer probing ?

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2009-06-08 10:07:51 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75339

I need to read some data from I2C eeprom and to configure the LCD driver. That's why I need I2C before FB...

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2009-06-08 10:14:00 Re: general driver question

Michael Hennerich (GERMANY)

Message: 75340 Read your i2c eeprom in u-boot and pass stuff via the kernel command

line.

-Michael

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2009-06-08 10:14:04 Re: general driver question

Mike Frysinger (UNITED STATES)

Message: 75341

i think you're doing it wrong. framebuffer configuration is not done in the probe function. it is done in the open function.

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2009-06-08 10:33:34 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75342

Thenks for the suggestion!

If I have no other chance I'll see how to do that.

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2009-06-08 10:34:56 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75343

the configuration is on 'open()' function, but I need to know some parameters (like screen size, etc.) at the probe time, as there the dma memory is reserved.

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2009-06-08 10:37:51 Re: general driver question

Mike Frysinger (UNITED STATES)

Message: 75344

there is no reason you cant delay the dma allocation to open() as well ... it isnt like the dma memory will be used at any point before that

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2009-06-08 10:42:56 Re: general driver question

Michael Hennerich (GERMANY)

Message: 75345 Mike,

fbcon will open the fb pretty early in the boot process.

At this point there is no i2c driver available.

-Michael

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2009-06-08 10:43:41 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75346

What about the 'fbinfo' structure and 'register_framebuffer(fbinfo)' call? The LCD data is used in this structure also.

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2009-06-08 10:46:06 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75347

... yes, that's what I observe - the I2C is attached much after the fb driver is finished...

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2009-06-08 10:55:37 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75348

... can I wait in the LCD driver for a I2C (with an error code from I2C) ?

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2009-06-08 11:09:11 Re: general driver question

Michael Hennerich (GERMANY)

Message: 75352 You can put your fb initialization/registration into the i2c_probe

callback.

This way your fb get's registered the time you know that i2c bus driver

is available.

-Michael

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2009-06-08 11:14:41 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75354

What about 'fbinfo'? Isn't it needed at FB probe? ... I have info to fill in this structure from the I2C eeprom...

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2009-06-08 11:21:09 Re: general driver question

Michael Hennerich (GERMANY)

Message: 75355 As I said - you will call

register_framebuffer(fbinfo);

from i2c probe callback.

You init function will only call i2c_add_driver()

static int __init yourfb_init(void)

{

return i2c_add_driver(&yourfb _driver);

}

module_init(yourfb_init);

-Michael

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2009-06-08 12:05:32 Re: general driver question

Nikolay Chokoev (IRELAND)

Message: 75359

That means that all initializations will be moved after the i2c is done... then I suppose I have to return success for lcd_probe(), lcd_open(), etc, and to initialize the hardware once I have i2c.

What will happen if i2c fails? (The LCD driver returned 'OK' but is not initialized)

...or I'm missing something?

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2009-06-08 13:12:11 Re: general driver question

Michael Hennerich (GERMANY)

Message: 75366 >...or I'm missing something?

I think so - there won't be open, etc. without register fb.

You simply move all stuff you have today in your probe function to the

i2c probe...

-Michael

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2009-06-09 05:34:59 Re: general driver question