[PATCH v3] input: MXC: add mxc-keypad driver to support the Keypad Port present in the mxc application processors family.

[Alberto Panizzo]

Hi,
On mer, 2010-01-27 at 18:03 +0100, Lothar Waßmann wrote:
> Hi,
> 
> Alberto Panizzo writes:
> > On mer, 2010-01-27 at 15:52 +0100, Lothar Waßmann wrote:
> > > Hi,
> > > 
> > > Alberto Panizzo writes:
> > > > On mer, 2010-01-27 at 13:18 +0100, Lothar Waßmann wrote:
> > > > > Hi,
> > > > > 
> > > > > Alberto Panizzo writes:
> > > > > > > > +	irq = platform_get_irq(pdev, 0);
> > > > > > > > +	if (irq < 0) {
> > > > > > > > +		dev_err(&pdev->dev, "failed to get keypad irq\n");
> > > > > > > > +		return -ENXIO;
> > > > > > > > +	}
> > > > > > > >
> > > > > > > This should be -ENODEV.
> > > > > > > 
> > > > > > Lot of reference keyboard driver use -ENXIO..
> > > > > > May should be better: return irq ?
> > > > > > 
> > > > > Yes, of course. If a function returns an error code that should be
> > > > > promoted to the caller instead of inventing a new error code.
> > > > > 
> > > > > 
> > > > > Lothar Waßmann
> > > > 
> > > > But, errno.h say:
> > > > #define ENXIO           6                // Device not configured
> > > > #define ENODEV          19               // Operation not supported by device
> > > > 
> > > What errno.h file is that?
> > > I have:
> > > ./include/asm-generic/errno-base.h:#define      ENXIO            6      /* No such device or address */
> > > ./include/asm-generic/errno-base.h:#define      ENODEV          19      /* No such device */
> > > 
> > > AFAIK ENXIO is used when actual I/O has been attempted. But in this
> > > case the driver is still being configured and did not do any I/O yet.
> > > 
> > > 
> > > Lothar Waßmann
> > 
> > The errno.h that I propose is a googled one and the kernel-one do not explain well..
> > Not for fighting, I wont understand.
> > 
> > In drivers/base/platform.c:
> > 
> > /**
> >  * platform_get_irq - get an IRQ for a device
> >  * @dev: platform device
> >  * @num: IRQ number index
> >  */
> > int platform_get_irq(struct platform_device *dev, unsigned int num)
> > {
> > 	struct resource *r = platform_get_resource(dev, IORESOURCE_IRQ, num);
> > 
> > 	return r ? r->start : -ENXIO;
> > }
> > 
> > If there isn't the irq resource asked platform_get_irq return ENXIO.
> > 
> The POSIX spec says:
> |[ENXIO]
> |    No such device or address. Input or output on a special file
> |refers to a device that does not exist, or makes a request beyond the
> |capabilities of the device. It may also occur when, for example, a
> |tape drive is not on-line. 

And I am not doing any I/O, while I am requesting something that is beyond
the capability defined in platform_data.

While 
|[ENODEV]
|  No such device. An attempt was made to apply an inappropriate function 
|to a device; for example, trying to read a write-only device such as a printer.

And:
-the device is present (registered in the driver model) 
-I am not trying to apply an inappropriate function.. 

Maybe the problem have to be attacked form another point of view:
Platform resources are parameters of the driver, the absence of IRQ and IO mem
would be considered as wrong parameters so the error should be EINVAL.

> 
> http://www.opengroup.org/onlinepubs/000095399/functions/xsh_chap02_03.html
> 
Bookmarked!!!! :)