On Wed, Apr 03, 2013 at 06:11:26PM +0200, Michel Dänzer wrote:
On Mit, 2013-04-03 at 09:57 -0400, Jerome Glisse wrote:
On Wed, Apr 3, 2013 at 5:37 AM, Michel Dänzer michel@daenzer.net wrote: On Die, 2013-04-02 at 14:13 -0400, Jerome Glisse wrote: > > Some might argue that we could just export the table content to > userspace, but that would loose information and possibly froze the > tile mode table forever as API.
The current index scheme already is de facto part of the API.
Only index 4,8,9,13 are part of current API no of the other are use.
The information we loose is what index > match to prefered surface format/type combination.How so? We can add descriptive names for the existing indices.
Look at my kernel patch, for instance i define : RADEON_TILE_MODE_COLOR_2D_32BPP
You can then query the kernel with RADEON_TILE_MODE_COLOR_2D_32BPP which gave you corresponding tile index and also correspond gb tile config.
http://people.freedesktop.org/~glisse/si2d-sol1/0001-drm-radeon-add-tile-mod...
And the tile mode > might be considered API as if kernel ever change what userspace expect > then we might break some userspace.Not sure how that could happen if the purpose of each index is clearly defined.
Well that's the question, are we happy, confident that we will never shuffle around the tile mode array. If so then we need to hard code tile index with a meaning and call it API. It's already the case for index 4,8,9,13
Maybe I'm missing the problem, but if libdrm_radeon were to get the tiling mode index chosen by radeonsi, and could retrieve the tiling parameters for each index from the kernel, it should be able to calculate things properly, shouldn't it?Let's not discuss about who/where the index is pick. No matter where it happens the question is do we want to hardcode tile index and make it api or do we want to hide it behind symbolic name allowing change in tile array (given that right now 4 value are already frozen). You can look at my kernel patch to see what i mean.
The layer of indirection for the indices seems like overengineering at this point. Even if the fixed indices stop being good enough for some reason in the future, how can we be sure now the layer of indirection will be good enough? So I think we shouldn't worry about that until that day may come.
Well i am fine with that but i just want to make sure everybody understand the implications.
Cheers, Jerome