From: Ben Skeggs Date: Wed, 6 Jan 2010 02:00:02 +0000 (+1000) Subject: drm/nv50: prevent a possible ctxprog hang X-Git-Tag: v3.0~6071^2~50^2~5 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=dc8d76cac942e7344a72ad18afb90fa46cf20bb4;p=platform%2Fkernel%2Flinux-amlogic.git 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 --- diff --git a/drivers/gpu/drm/nouveau/nouveau_irq.c b/drivers/gpu/drm/nouveau/nouveau_irq.c index 370c72c..919a619 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);