From f55ded764ce60f87463e33bfa3a32e2c44715581 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Sun, 12 Apr 2015 18:39:07 -0700 Subject: [PATCH] i965: Implement proper workaround for Gen4 GPU CONSTANT_BUFFER hangs. I finally managed to dig up some information on our mysterious GPU hangs. A wiki page from the Crestline validation team mentions that they found a GPU hang in "Serious Sam 2" (on Windows) with remarkably similar conditions to the ones we've seen in Google Chrome and glmark2. Apparently, if WM_STATE has "PS Use Source Depth" enabled, CC_STATE has most depth state disabled, and you issue a CONSTANT_BUFFER command and immediately draw, the depth interpolator makes a small mistake that leads to hangs. Most of the traces I looked at contained a CONSTANT_BUFFER packet immediately followed by 3DPRIMITIVE, or at least very few packets. It appears they also have "PS Use Source Depth" enabled - either at the hang, or a little before it. So I think this is our bug. The workaround is to emit a non-pipelined state packet after issuing a CONSTANT_BUFFER packet. This is really similar to the workaround I developed in commit c4fd0c9052dd391d6f2e9bb8e6da209dfc7ef35b. v2: Fix word-wrapping issues. Signed-off-by: Kenneth Graunke Reviewed-by: Francisco Jerez Reviewed-by: Matt Turner --- src/mesa/drivers/dri/i965/brw_curbe.c | 39 ++++++++++++++++++--------- 1 file changed, 26 insertions(+), 13 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_curbe.c b/src/mesa/drivers/dri/i965/brw_curbe.c index e45e2abd3fc..befd7a9538c 100644 --- a/src/mesa/drivers/dri/i965/brw_curbe.c +++ b/src/mesa/drivers/dri/i965/brw_curbe.c @@ -285,19 +285,6 @@ brw_upload_constant_buffer(struct brw_context *brw) */ emit: - /* Work around mysterious 965 hangs that appear to happen if you do - * two 3DPRIMITIVEs with only a CONSTANT_BUFFER inbetween. If we - * haven't already flushed for some other reason, explicitly do so. - * - * We've found no documented reason why this should be necessary. - */ - if (brw->gen == 4 && !brw->is_g4x && - (brw->ctx.NewDriverState & (BRW_NEW_BATCH | BRW_NEW_PSP)) == 0) { - BEGIN_BATCH(1); - OUT_BATCH(MI_FLUSH); - ADVANCE_BATCH(); - } - /* BRW_NEW_URB_FENCE: From the gen4 PRM, volume 1, section 3.9.8 * (CONSTANT_BUFFER (CURBE Load)): * @@ -317,6 +304,31 @@ emit: (brw->curbe.total_size - 1) + brw->curbe.curbe_offset); } ADVANCE_BATCH(); + + /* Work around a Broadwater/Crestline depth interpolator bug. The + * following sequence will cause GPU hangs: + * + * 1. Change state so that all depth related fields in CC_STATE are + * disabled, and in WM_STATE, only "PS Use Source Depth" is enabled. + * 2. Emit a CONSTANT_BUFFER packet. + * 3. Draw via 3DPRIMITIVE. + * + * The recommended workaround is to emit a non-pipelined state change after + * emitting CONSTANT_BUFFER, in order to drain the windowizer pipeline. + * + * We arbitrarily choose 3DSTATE_GLOBAL_DEPTH_CLAMP_OFFSET (as it's small), + * and always emit it when "PS Use Source Depth" is set. We could be more + * precise, but the additional complexity is probably not worth it. + * + * BRW_NEW_FRAGMENT_PROGRAM + */ + if (brw->gen == 4 && !brw->is_g4x && + (brw->fragment_program->Base.InputsRead & (1 << VARYING_SLOT_POS))) { + BEGIN_BATCH(2); + OUT_BATCH(_3DSTATE_GLOBAL_DEPTH_OFFSET_CLAMP << 16 | (2 - 2)); + OUT_BATCH(0); + ADVANCE_BATCH(); + } } const struct brw_tracked_state brw_constant_buffer = { @@ -324,6 +336,7 @@ const struct brw_tracked_state brw_constant_buffer = { .mesa = _NEW_PROGRAM_CONSTANTS, .brw = BRW_NEW_BATCH | BRW_NEW_CURBE_OFFSETS | + BRW_NEW_FRAGMENT_PROGRAM | BRW_NEW_FS_PROG_DATA | BRW_NEW_PSP | /* Implicit - hardware requires this, not used above */ BRW_NEW_URB_FENCE | -- 2.30.2