On Saturday, February 28, 2015 01:19:28 PM Ben Widawsky wrote: > On Sat, Feb 28, 2015 at 12:31:59AM -0800, Kenneth Graunke wrote: > > On Friday, February 27, 2015 10:22:10 AM Ben Widawsky wrote: > > > From the comments in the code: > > > > > > Called from intel_batchbuffer_flush before emitting MI_BATCHBUFFER_END > > > and > > > sending it off. > > > > > > This fixes a possible, unlikely infinite recursion in our batch flush > > > path. More > > > importantly it allows me to add some code here. > > > > > > The relevant part of the call chain for flush > > > intel_batchbuffer_flush()->brw_finish_batch(). The problem arises if > > > anything in > > > the time from intel_batchbuffer_flush, until brw_finish_batch ends up > > > calling > > > itself. This can happen as a result of a call to > > > intel_batchbuffer_begin()->intel_batchbuffer_require_space()->intel_batchbuffer_flush(). > > > > > > There are two possible cases today which can spawn this recursion. > > > 1. There is a ring switch occurring (impossible, see below) > > > 2. The ring is out of space (fairly unlikely) > > > > NAK. brw_finish_batch is for putting any last-minute commands in the > > batchbuffer before sending it off. > > > > Such commands must fit in the BATCH_RESERVED space (which is probably > > already large enough since SNB has a zillion workarounds). This > > eliminates reason #2. > > > > #1 means that you're trying to emit commands for the wrong ring, i.e. > > trying to do RCS workarounds in a BLT batch. This isn't what you want. > > Sorry you wasted your time looking at this. I had fixed both of what you > mentioned, but hadn't sent it out yet. It's fixed with a better commit > message here: > http://cgit.freedesktop.org/~bwidawsk/mesa/commit/?h=workarounds&id=f87c17e34eeac9d5e3f54c9b182090f8aede0284
I still don't understand the point - I see nothing in your code that would trigger a batch flush from brw_finish_batch. Any such code would be most certainly wrong. I think you can simply drop this and the rest of your updated series will continue working just fine.
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