Re: [PATCH 1/1] UIO: Add a write() function to enable/disable interrupts

Greg KH
2008-05-27T17:59:04Z

On Sun, May 25, 2008 at 12:22:20AM +0200, Thomas Gleixner wrote:
> On Fri, 23 May 2008, Greg KH wrote:
>
> > On Fri, May 23, 2008 at 01:55:57PM +0200, Hans J. Koch wrote:
> > > Sometimes it is necessary to enable/disable the interrupt of a UIO device
> > > from the userspace part of the driver. With this patch, the UIO kernel driver
> > > can implement an "irqcontrol()" function that does this. Userspace can write
> > > an s32 value to /dev/uioX (usually 0 or 1 to turn the irq off or on). The
> > > UIO core will then call the driver's irqcontrol function.
> >
> > Why not just a new sysfs file for the uio device, irq_enabled, or
> > something like that? That way our main read/write path is left alone.
>
> It makes a certain amount of sense to use write. You hold the device
> file descriptor anyway for the read (wait for interrupt) operation,
> so using the same file descriptor is not a too bad idea:
>
> while (!stop) {
>
> /* wait for interrupt */
> read(fd);
>
> do_stuff();
>
> /*reenable interrupt */
> write(fd);
> }
>
> I thought about using a sysfs entry for a while, but looking at the
> actual use case made the write() solution a more natural choice.

Ok, that makes sense, I can accept this.

Anyone care to respin the patches with the latest updates and send them
to me?

thanks,

greg k-h