On Tue, 2023-06-13 at 16:20 +0200, Danilo Krummrich wrote: > I'm definitely up improving the existing documentation. Anything in > particular you think should be described in more detail? > > - Danilo Hi Danilo, As I said, with inexperience it's possible I missed what I was looking for in the existing documentation, which is highly detailed in regard to how it deals with operations, but usage was where I fell down. If I understand there are three ways to use this, which are: 1) Using drm_gpuva_insert() and drm_gpuva_remove() directly using stack va objects. 2) Using drm_gpuva_insert() and drm_gpuva_remove() in a callback context, after having created ops lists using drm_gpuva_sm_[un]map_ops_create(). 3) Using drm_gpuva_[un]map() in callback context after having prealloced a node and va objects for map/remap function use, which must be forwarded in as the 'priv' argument to drm_gpuva_sm_[un]map(). The first of these is pretty self-explanatory. The second was also fairly easy to understand, it has an example in your own driver, and since it takes care of allocs in drm_gpuva_sm_map_ops_create() it leads to pretty clean code too. The third case, which I am using in the new PowerVR driver did not have an example of usage and the approach is quite different to 2) in that you have to prealloc everything explicitly. I didn't realise this, so it led to a fair amount of frustration. I think if you're willing, it would help inexperienced implementers a lot if there were some brief 'how to' snippets for each of the three use cases. Thanks, Donald
