On Wed, Mar 15, 2006 at 18:54:08 +0500, Fawad Lateef wrote:
> On 3/15/06, taha siddiqi <tawushafeez@xxxxxxxxx> wrote:
> > Hi....
> > I am trying to read data from my laptop's (thinkpad R51) parallel port
> > (similar to the example in Linux Device Drivers 3rd Edition).
> > But, everytime i am reading the data it always comes to be 0xFF(255) ....
> > I even tried the following loop in my write function (struct file_operations)
> > while(count--){
> > printk("writing %x\n", *ptr);
> > out(*(ptr++), port);
> > wmb();
> > printk("reading data : %x\n", inb(port));
> > }
> > but the debug message in log shows something like
> > writing 116
> > reading 255
> > writing 78
> > reading 255
> > ...
> > ...
>
> There are different modes for Parallel Port (AFAIR like
> bi-directional, EPP or so, just google for it) which you have to
> configure to bi-directional in your board bios setup (its by-default
> not configured as bi-directional). So you are only able to read the
> data not able to write and all your write operations does nothing.
> CMIIW
The other way round, no? You can only write, but it gives nothing sensible
when reading.
--
Jan 'Bulb' Hudec <bulb@xxxxxx>
Attachment:
signature.asc
Description: Digital signature
