UCB1400 Touchscreen IRQ

UCB1400 Touchscreen IRQ

[Peter Ma]

I apologize for contacting you directly.  I believe you are the
maintainer of the Linux input drivers.
If there is a forum I ought to be checking, please point me in that
direction.

The UCB1400 touchscreen driver (input/touchscreen/ucb1400_ts.c)
currently uses an interrupt autoprobe to self-discover its interrupt.
The probe_irq_on/off functions indicate interrupts using a 32-bit field.
I am using a SoC (Atmel AVR32), in which the available external
interrupts are enumerated starting from 64, which cannot be represented
in a 32-bit field.  Thus interrupt autoprobing always fails.

I believe the solution is to somehow pass a IRQ down from the driver
instantiation, and modify ucb1400_ts_probe() to check for the IRQ number
before attempting to autoprobe.

In a couple of board setups I have seen (e.g.
arch/arm/mach-pca/cm-x270.c), ucb1400_ts is instantiated as a
"platform_device", eventhough the driver is written as a regular
"device".  Normally, something board-specific like an IRQ assignment is
passed in platform_device->resource, but I do not see how ucb1400_ts
device would be able to fetch that.

I see there is a device.platform_data, and I see a platform_device.dev.
I attempted to pass a pointer through
platform_device->dev.platform_data, but it did not appear to make it
through to device.platform_data down in the driver.

Is there a correct method for passing information (like IRQ assignment)
into a "device" driver, like ucb1400_ts?

I am quite new to linux drivers, so any guidance you can provide would
be greatly appreciated.

Thanks & Regards,
________________________________________________________________
Peter W.W. Ma                | email:  peterma@zeugmasystems.com
Principal Engineer           | tel:    +1 604 247-3269
Zeugma Systems               | fax:    +1 604 247-3251
Suite 250, 13571 Commerce Parkway, Richmond, BC, Canada, V6V 2R2
 

Re: UCB1400 Touchscreen IRQ

[Dmitry Torokhov]

Hi Peter,

On Sun, Feb 24, 2008 at 10:24:11PM -0800, Peter Ma wrote:
> I apologize for contacting you directly.  I believe you are the
> maintainer of the Linux input drivers.
> If there is a forum I ought to be checking, please point me in that
> direction.
> 
> The UCB1400 touchscreen driver (input/touchscreen/ucb1400_ts.c)
> currently uses an interrupt autoprobe to self-discover its interrupt.
> The probe_irq_on/off functions indicate interrupts using a 32-bit field.
> I am using a SoC (Atmel AVR32), in which the available external
> interrupts are enumerated starting from 64, which cannot be represented
> in a 32-bit field.  Thus interrupt autoprobing always fails.
> 
> I believe the solution is to somehow pass a IRQ down from the driver
> instantiation, and modify ucb1400_ts_probe() to check for the IRQ number
> before attempting to autoprobe.
> 
> In a couple of board setups I have seen (e.g.
> arch/arm/mach-pca/cm-x270.c), ucb1400_ts is instantiated as a
> "platform_device", eventhough the driver is written as a regular
> "device".  Normally, something board-specific like an IRQ assignment is
> passed in platform_device->resource, but I do not see how ucb1400_ts
> device would be able to fetch that.
> 
> I see there is a device.platform_data, and I see a platform_device.dev.
> I attempted to pass a pointer through
> platform_device->dev.platform_data, but it did not appear to make it
> through to device.platform_data down in the driver.
> 
> Is there a correct method for passing information (like IRQ assignment)
> into a "device" driver, like ucb1400_ts?
> 
> I am quite new to linux drivers, so any guidance you can provide would
> be greatly appreciated.
> 

I apologize for not responding earlier, I was not able to spend much
time on the kernel for the last several months..

I believe your issue is fixed by the following patch from Vernon
Snauder.

-- 
Dmitry

From: Vernon Sauder <vernoninhand@gmail.com>

Input: ucb1400_ts - IRQ probe fix

The UCB1400 driver IRQ probe code fails to find an interrupt if all
the interrupts in the range 0-31 are nonprobe-able. This patch
removes the check of the return value so interrupts above 31 can be
detected.

Tested on InHand Fingertip4 PXA270 board.

Signed-off-by: Vernon Sauder <vsauder@inhand.com>
Acked-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
 drivers/input/touchscreen/ucb1400_ts.c |    4 ----
 1 file changed, 4 deletions(-)

Index: work/drivers/input/touchscreen/ucb1400_ts.c
===================================================================
--- work.orig/drivers/input/touchscreen/ucb1400_ts.c
+++ work/drivers/input/touchscreen/ucb1400_ts.c
@@ -427,10 +427,6 @@ static int ucb1400_detect_irq(struct ucb
 	unsigned long mask, timeout;
 
 	mask = probe_irq_on();
-	if (!mask) {
-		probe_irq_off(mask);
-		return -EBUSY;
-	}
 
 	/* Enable the ADC interrupt. */
 	ucb1400_reg_write(ucb, UCB_IE_RIS, UCB_IE_ADC);