On Mon, Apr 01, 2002 at 07:38:18AM -0700, Jens Owen wrote:
> Alan Hourihane wrote:
> > 
> > On Fri, Mar 29, 2002 at 09:21:52PM -0700, Jens Owen wrote:
> > > I've checked into the drmcommand-0-0-1-branch the complete conversion of
> > > the Radeon driver suite to the drmCommand interface.  Take a look, and
> > > let me know if you see any problems, or if you have any questions.
> > >
> > > If anyone is interested in converting any of the other drivers, please
> > > let me know and we'll coordinate the work.  I won't be able to get to
> > > any of the other drivers until sometime next week.
> > >
> > Jens,
> > 
> > I see you've got the four drmCommand*() functions but I'm wondering
> > if there's a need for these 4 and it could be reduced to just the one.
> > 
> > The command itself identifies it's direction - so why do we specifically
> > need to pass this ?
> 
> Alan,
> 
> My original definition of the functions encoded alot of information just
> like a regular Linux IOCTL.  In addition to the request index, it also
> included the device type, direction of data transfer and size of data
> structure.  However, with the concern about the interface not being
> generic, I broke away from the Linux encoding and made the interface
> very generic.  Now, the function is only the request index and does
> contain the direction of other information.  This also addresses any
> potential concern about the overhead of decoding and re-encoding bit
> fields for none Linux OS's.  My think was to be explicit with each
> parameter and encode it at the OS dependent level inside the drmCommand
> implementation.
> 
> We could add an additional parameter for direction, and get down to one
> call...but I didn't know how important that was vs. the overhead of
> creating run time conditions for something that was static at compile
> time.
>  
> > We could just do drmCommand(fd, FUNCTION, NULL, NULL); for the current
> > drmCommandNone() call to keep the interface the same.
> 
> If we encode the size and type as well, we get back to the original
> Linux semantics that made everyone scream that this wasn't portable.  I
> believe EVERYTHING we've covered to date is portable.  One extreme is
> the Linux semantics I started with...the other is what I've got now,
> very generic semantics.  You're suggesting something in the middle.  I'm
> good with any of these solutions, but I would like to avoid changing
> this more than once, just from a development time perspective.
> 
O.k. Understand what your saying.

Alan.

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