Chad Versace <chad.vers...@linux.intel.com> writes: > On Mon, Mar 24, 2014 at 09:07:32AM +1000, Dave Airlie wrote: >> On Sat, Mar 8, 2014 at 12:13 AM, Pohjolainen, Topi >> <topi.pohjolai...@intel.com> wrote: >> > On Mon, Mar 03, 2014 at 01:19:48PM +1000, Dave Airlie wrote: >> >> There is a comment and two checks in the i965 dma-buf importer, >> >> >> >> * Images originating via EGL_EXT_image_dma_buf_import can be used only >> >> * with GL_OES_EGL_image_external only. >> >> >> >> however I can't find any reference to this in the spec txt, and >> >> removing the checks make my test app run fine using TEXTURE_2D. >> > >> > You are correct that there is nothing in the spec about this, but it also >> > leaves >> > it open for the driver to choose on which buffers it allows the external >> > sampling. >> > After quite a bit of debate on when/where it would be safe to use >> > dma-buffers, >> > it was decided that we simply allow dma-buffers for external sampling only >> > - >> > that extension already restricts the use for single-miplevel and read-only >> > which is exactly what we wanted. >> > The same time it wasn't clear what kind of sources we should allow for >> > external >> > sampling (besides dma), and hence we simply kept things as they were >> > before - >> > none other. Note that before the introduction of dma-buffers the image >> > external >> > extension wasn't enabled at all on i965. >> > >> >> This is a really bad idea, since it means you can't use dma-buf >> imported things with standard shader programs, if I want to import a >> dma-buf I shouldn't have to write specific shader programs or use >> special bindings, unless the spec says so. > > Bringing your request to its logical conclusion... > >> Either the spec should be more restrictive, or the implementation >> shouldn't have arbitrary differences from what other implementations >> could do. > > ...leads to disaster. It's naive to expect each implementation to support > what other implementations *could*, or even *currently* do. > > Are you prepared to impelement support for these horrorshows? > > A. Import a YUV EGLImage backed by two dma_bufs (Y in the first, UV in > the second) as a GL_TEXTURE_EXTERNAL_OES and transparently handle the > YUV->RGB transcode in your shader code generator? Because, iirc, ARM's > EGL/GLES2 stack supports that for Chrome. > > B. Same idea as A, but support importing the image as a GL_TEXTURE_2D > and again transparently handle the YUV->RGB transcode. > Because, for all we know, ARM's stack may support that too.
Ignore YUV for now. YUV is the thing that image_external is for, with all of its weird requirements and unspecifiedness and making your images undefined on import. What airlied wants (I think) and what I definitely want, is to import normal ARGB dma_bufs and use them with GL_TEXTURE_2D. I think we can do this, and it's just a matter of making some solid tests to make sure we're not screwing up sibling management, and that the offset/stride/etc handling all works.
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