Commit 7978b9cf authored by Ben Skeggs's avatar Ben Skeggs
Browse files

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: default avatarBen Skeggs <>
parent bbb8c3d8
......@@ -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));
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