Saturday, October 4, 2014

Freedreno Update

A number of people have recently asked what is new with freedreno.  It had been a while since posting an update.. and, well, not everyone watches mesa commit logs for fun, or watches #freedreno on freenode, so it seemed like time for another semi-irregular freedreno blog post.

The tl;dr version: recently it has been a lot of robustness, and bug fixes and smaller feature implementation for piglit, etc.  No one big exciting feature this time.. but lots of little things adding up to make freedreno on a3xx more complete and mature.

And an obligatory screenshot, just because:

(Yeah, webgl should probably be faster in chrome/chromium.. but not packaged for fedora, and chrome build system was invented by someone who wants to make compiling their src as difficult as possible.)


On the mesa/gallium driver front, the big news is that earlier this week we finally achieved a 90% pass ratio for piglit.  (In fact, 90.4%)  To put this in perspective, a little over six months ago freedreno was at just 50% pass.  Since June, we have added around 600 passing tests.  In fact in the last week, an additional ~50 tests are passing, which bumps us up to 91% pass.

For those who are not familiar with it, piglit is an open source OpenGL test suite.  Since the mesa developers are quite good about adding new test cases to piglit whenever adding a new feature/extension to mesa, it is a very comprehensive test suite.  The down side, if you could call it that, is that it has a lot more OpenGL tests compared to OpenGLES (at least for GLES < 3.0).  So getting the pass ratio up involved implementing (and in some cases emulating) a number of features that the blob ES-only driver does not support.  Fortunately enough of the registers and bitfields are known at this point that trial and error with educated guesses (and then see which guesses make piglit tests pass) has worked out reasonably well for some features.  Other features, like GL_CLAMP and two sided color, we need to emulate in the shader, which was implemented as a TGSI to TGSI pass in order to hopefully be useful for other gallium drivers for GLES class hardware.  (And, in fact both of those are things that at least some of the desktop drivers need to emulate as well.)

And big thanks to Ilia Mirkin for a lot of advice and some patches for the failing piglits.  Ilia has also started sending a lot of patches for the compiler to flesh out integer support, add new instructions (in particular texture sample instructions), and other things that will be needed for GL3/GLES3.  In fact as a result of his work, we are already at ~85% pass for GL3 despite missing some bullet-point features!


On the xf86-video-freedreno front, over the last few months we have gained server managed fd's and OutputClass support (so that a sufficiently new xserver can auto-pick the correct driver, like we have had for a long time on desktop/pci systems).  And a hot-off-the-presses 1.3.0 release with a handful of robustness fixes.  I strongly recommend to upgrade.


These last few kernel releases have seen a significant improvement in the state of apq8064/ifc6410 support upstream.  As of the 3.17 kernel, the main things missing to work on a pure-upstream[1] kernel are the rpm/rpm-regulators iommu drivers.  The linaro folks have been a big help there.  In particular, their integration branch, which consists of latest upstream plus in-flight patches, is significantly easier than tracking all the relevant kernel mailing lists.

For drm/msm, the last few kernel releases have seen:  some basic gpu perf and logging debugfs features, DT support for mdp4 (display controller version in apq8064), LVDS and multi-monitor support for mdp4, and mdp5 v1.3 support from qcom for upcoming devices.  And of course bug fixes!

[1] Ie. Linus's tree... kernel-msm or AOSP is not upstream, for any android type's who were confused about that.

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