Re: Xilinx: hwicap driver comments

[Jiri Slaby]

On 02/07/2008 11:31 PM, Stephen Neuendorffer wrote:
> > Few comments I have:
> > - release f_op retval is silently ignored, I guess you will get your
> device into
> > undefined state when the first function fails (esp. when you interrupt
> the sem)
>
> Hmm..  hadn't realized that.  I'm open to suggestions on how to do this
> better.  The real reason why the synchronization is there is to make
> sure that only one client is using the device at a time, using the
> is_open flag.

just mutex_lock(); that need not be interrupted.

> > - semaphores are deprecated
> > - class_device_create is deprecated
>
> What is preferred?

device_create(); and pass the struct device as a parent when you are at it. 
Otherwise it will be in /sys/*/virtual/* I suppose.

> > - don't understand this:
> >                  memcpy(kbuf, drvdata->read_buffer, bytes_remaining);
> >                  drvdata->read_buffer_in_use = bytes_remaining;
> >                  free_page((unsigned long)kbuf);
>
> The physical device only generates/accepts complete words, the intention
> is to account for the possibility that a read does not read complete
> words, and to fulfill the read whenever possible.
> It's arguable that read() and write() should not accept or return
> partial words, I suppose

OK, but why are you copying anything to buffer which you free 2 lines below?
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