Beagleboard xM Rev.B touchscreen not working on Linux

[washburn]

Hello.

I purchased the 7 inch LCD w/ Touchscreen from e-bay to use with my BB. xM Rev. B.

In WinCE everything works ok, but in Linux the Touchscreen refuses to work.
I have already tried recompiling Kernel, rootfs, u-boot, pretty much everything.
I even used the validation u-boot and kernel from http://gitorious.org/beagleboard-validation, changing the panel and adding the touchscreen driver in board-omap3beagle.c but it didn't work.

After some further tests I found that, in the file
./drivers/input/touchscreen/ads7846.c,
the following function

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static int ads7846_read12_ser(struct device *dev, unsigned command)
{
	struct spi_device	*spi = to_spi_device(dev);
	struct ads7846		*ts = dev_get_drvdata(dev);
	struct ser_req		*req = kzalloc(sizeof *req, GFP_KERNEL);
	int			status;
	int			use_internal;

	if (!req)
		return -ENOMEM;

	spi_message_init(&req->msg);

	/* FIXME boards with ads7846 might use external vref instead ... */
	use_internal = (ts->model == 7846);
	
	printk("ads7846: ts->model - %d\n", ts->model);	
	printk("ads7846: use_internal - %s\n", (use_internal?"true":"false"));

	/* maybe turn on internal vREF, and let it settle */
	if (use_internal) {
		printk("ads7846: entered use_internal method\n");
		req->ref_on = REF_ON;
		req->xfer[0].tx_buf = &req->ref_on;
		req->xfer[0].len = 1;
		spi_message_add_tail(&req->xfer[0], &req->msg);

		req->xfer[1].rx_buf = &req->scratch;
		req->xfer[1].len = 2;

		/* for 1uF, settle for 800 usec; no cap, 100 usec.  */
		req->xfer[1].delay_usecs = ts->vref_delay_usecs;
		spi_message_add_tail(&req->xfer[1], &req->msg);
	}

	/* take sample */
	req->command = (u8) command;
	req->xfer[2].tx_buf = &req->command;
	req->xfer[2].len = 1;
	spi_message_add_tail(&req->xfer[2], &req->msg);

	req->xfer[3].rx_buf = &req->sample;
	req->xfer[3].len = 2;
	spi_message_add_tail(&req->xfer[3], &req->msg);

	/* REVISIT:  take a few more samples, and compare ... */

	/* converter in low power mode & enable PENIRQ */
	req->ref_off = PWRDOWN;
	req->xfer[4].tx_buf = &req->ref_off;
	req->xfer[4].len = 1;
	spi_message_add_tail(&req->xfer[4], &req->msg);

	req->xfer[5].rx_buf = &req->scratch;
	req->xfer[5].len = 2;
	CS_CHANGE(req->xfer[5]);
	spi_message_add_tail(&req->xfer[5], &req->msg);

	ts->irq_disabled = 1;
	disable_irq(spi->irq);
	
	status = spi_sync(spi, &req->msg);
	
	printk("ads7846: status = %d\n", status);
	
	ts->irq_disabled = 0;
	enable_irq(spi->irq);


	if (status == 0) {
		/* on-wire is a must-ignore bit, a BE12 value, then padding */
		status = be16_to_cpu(req->sample);
		status = status >> 3;
		status &= 0x0fff;
	}

	kfree(req);
	return status;
}

or more specifically

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status = spi_sync(spi, &req->msg);

allways returns 0.
Thus, in the function
static int __devinit ads7846_probe(struct spi_device *spi)
the following code

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	err = ads7846_read12_ser(&spi->dev,
			  READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);

	/* if sample is all 0's or all 1's then there is no device on spi */	
	if ( (err == 0x000) || (err == 0xfff)) {
		dev_info(&spi->dev, "no device detected, test read result was 0x%08X\n", err);
		err = -ENODEV;
		goto err_free_irq;
	}

always frees the irq, disabling the touchscreen.

The touchscreen driver implementation I adopted is equal to the one on board-omap3evm.c, or the one from the android sources that came in the data partition of the sd card.

Has anyone experienced this situation or know how to solve it?
I would appreciate any help you could give me.

Thank you

Oh, and forgot to mention my final tests were performed with Angstrom, and the command

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dmesg | grep ads7846

returns the following:

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ads7846 spi3.0: setup mode 0, 8 bits/w, 1500000 Hz max --> 0
ads7846 spi3.0: touchscreen, irq 293
ads7846 spi3.0: no device detected, test read result was 0x00000000 

[esky-sh]

Did you check pin mux configuration for SPI on Touch screen? I suggest you use printk to dump some contents of registers.

[washburn]

Yes, I did.

When running ts_calibrate I'm getting some strange values now, when available I'll post here.

[samertfl]

Can you please post your code if you have it working on Angstrom?