From 7978b9cfa59133a34aaad420e447c2a29d5c6152 Mon Sep 17 00:00:00 2001
From: Ben Skeggs <bskeggs@redhat.com>
Date: Wed, 6 Jan 2010 12:00:02 +1000
Subject: [PATCH] drm/nv50: prevent a possible ctxprog hang
The below is mainly an educated guess at what's going on, docs would
sure be handy... NVIDIA? :P
It appears it's possible for a ctxprog to run even while a GPU exception
is pending. The GF8 and up ctxprogs appear to have a small snippet of
code which detects this, and stalls the ctxprog until it's been handled,
which essentially looks like:
if (r2 & 0x00008000) {
r0 |= 0x80000000;
while (r0 & 0x80000000) {}
}
I don't know of any way that flag would get cleared unless the driver
intervenes (and indeed, in the cases I've seen the hang, nothing steps
in to automagically clear it for us). This patch causes the driver to
clear the flag during the PGRAPH IRQ handler.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
---
drivers/gpu/drm/nouveau/nouveau_irq.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/nouveau/nouveau_irq.c b/drivers/gpu/drm/nouveau/nouveau_irq.c
index 370c72c968d1..919a619ca7fa 100644
--- a/drivers/gpu/drm/nouveau/nouveau_irq.c
+++ b/drivers/gpu/drm/nouveau/nouveau_irq.c
@@ -635,6 +635,7 @@ nv50_pgraph_irq_handler(struct drm_device *dev)
if ((nv_rd32(dev, 0x400500) & isb) != isb)
nv_wr32(dev, 0x400500, nv_rd32(dev, 0x400500) | isb);
+ nv_wr32(dev, 0x400824, nv_rd32(dev, 0x400824) & ~(1 << 31));
}
nv_wr32(dev, NV03_PMC_INTR_0, NV_PMC_INTR_0_PGRAPH_PENDING);