Re: [Dri-devel] Re: DRM and pci_driver conversion

On Mon, Oct 27, 2003 at 06:13:32PM -0800, Linus Torvalds wrote:

..
So the thing should really just have 
 - discovery and attach/detach
 - interrupt event notification (and it can't just be "an interrupt 
   happened" - the interrupt driver actually has to know enough to ACK the
   interrupt, so that we can tell user space that an interrupt happened 
   without having to disable the interrupt until the event goes away)
 - serialization (ie a lock) and waiting for events ("engine idle" or 
   "command queue less than half full")
 - DMA arbitration and setup.
[....]
So the low-level driver wouldn't know about palettes or cursors or any 
"high-level" concepts like that. It would have a few locks to make sure 
that the users that try to access the things don't stop on each other, 
nothing more (maybe the locks themselves would be grouped into "palette 
lock" vs "cursor lock" vs "DMA engine lock" since hardware may be threaded 
enough to allow it, but the point is that the low-level driver wouldn't 
actually _do_ anything, it only allows others to do what they want without 
stomping on each others toes).

Sounds like a good idea. Simple Is Better.

Now, would that "DMA arbitration" include
"submit a chunk o dma memory for GPU processing",

or would it just allow [whatever] to map the registers, and basically say,
"I'll tell you when something completes (aka sends an interrupt)
 but it's up to you to START it"





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