[PATCH v2 1/3] drm/nouveau/fifo/nv04: filter benign CACHE_ERROR from Mesa NV50 bind probe

[Marek Czernohous <mczernohous@gmail.com>]

From: Marek Czernohous <marek@czernohous.de>

The Mesa userspace driver issues a method-0x0060 / data-0xbeef02xx
binding probe on Tesla GPUs that ends up triggering CACHE_ERROR in the
PFIFO interrupt handler. The probe is harmless and recovers cleanly,
but it floods dmesg at error level on every X/Wayland session start.

Filter that specific pattern down to debug level so dmesg stays clean
while real CACHE_ERROR conditions are still logged at error level.

Tested on an Apple Mac mini Late 2009 (MCP79, NVAC 0xac080b1): dmesg has
no CACHE_ERROR spam during normal operation, the previously visible
beef02xx pattern now only appears at debug level.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Marek Czernohous <marek@czernohous.de>
---
 .../gpu/drm/nouveau/nvkm/engine/fifo/nv04.c   | 25 ++++++++++++++-----
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/nv04.c b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/nv04.c
index c4b8e567d86f..fa13cd55b593 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/nv04.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/nv04.c
@@ -327,12 +327,25 @@ nv04_fifo_intr_cache_error(struct nvkm_fifo *fifo, u32 chid, u32 get)
 
 	if (!(pull0 & 0x00000100) ||
 	    !nv04_fifo_swmthd(device, chid, mthd, data)) {
-		chan = nvkm_chan_get_chid(&fifo->engine, chid, &flags);
-		nvkm_error(subdev, "CACHE_ERROR - "
-			   "ch %d [%s] subc %d mthd %04x data %08x\n",
-			   chid, chan ? chan->name : "unknown",
-			   (mthd >> 13) & 7, mthd & 0x1ffc, data);
-		nvkm_chan_put(&chan, flags);
+		/*
+		 * Filter benign Mesa NV50 bind probe: mthd 0x0060 with
+		 * data 0xbeef02xx is a harmless userspace probe on Tesla
+		 * GPUs and does not indicate an actual error condition.
+		 * Demote to debug to keep dmesg clean while still catching
+		 * real CACHE_ERROR events.
+		 */
+		if ((mthd & 0x1ffc) == 0x0060 &&
+		    (data & 0xffffff00) == 0xbeef0200) {
+			nvkm_debug(subdev, "CACHE_ERROR - ch %d subc %d mthd %04x data %08x (benign, skipped)\n",
+				   chid, (mthd >> 13) & 7, mthd & 0x1ffc, data);
+		} else {
+			chan = nvkm_chan_get_chid(&fifo->engine, chid, &flags);
+			nvkm_error(subdev, "CACHE_ERROR - "
+				   "ch %d [%s] subc %d mthd %04x data %08x\n",
+				   chid, chan ? chan->name : "unknown",
+				   (mthd >> 13) & 7, mthd & 0x1ffc, data);
+			nvkm_chan_put(&chan, flags);
+		}
 	}
 
 	nvkm_wr32(device, NV04_PFIFO_CACHE1_DMA_PUSH, 0);
-- 
2.54.0