On Mon, 5 Dec 2011 14:57:09 -0800, Jesse Barnes <[email protected]> wrote: > On Wed, 30 Nov 2011 13:54:47 -0800 > Eric Anholt <[email protected]> wrote: > > > On Wed, 30 Nov 2011 03:42:00 +0000, Ben Widawsky <[email protected]> wrote: > > Non-text part: multipart/signed > > > On Tue, Nov 29, 2011 at 04:47:57PM -0800, Eric Anholt wrote: > > > > On Mon, 28 Nov 2011 18:48:04 -0800, "Keith Packard" <[email protected]> > > > > wrote: > > > > Non-text part: multipart/mixed > > > > Non-text part: multipart/signed > > > > > > > > > > Just reading through vol1c.4 of the bspec this evening and found > > > > > something odd. > > > > > > > > > > Bit 11 of MI_MODE is "Invalidate UHPTR enable". > > > > > Bit 12 of MI_MODE is "MI_FLUSH Enable" > > > > > > > > > > And, yet, in i915_reg.h: > > > > > > > > > > #define MI_MODE 0x0209c > > > > > # define VS_TIMER_DISPATCH (1 << 6) > > > > > # define MI_FLUSH_ENABLE (1 << 11) > > > > > > > > > > Are we off-by-one on MI_FLUSH_ENABLE? Seems like this would cause > > > > > serious problems... > > > > > > > > I think we are. On the other hand, based on actual behavior plus > > > > reading of simulator, I believe that the bit does nothing, regardless. > > > > > > I do not think so. We've (Chris, I, and perhaps Jesse?) been through > > > this excercise at least twice before, and both times resulted in hangs > > > when we switched to bit 12 on Ironlake, not sure about other platforms. > > > > There is no MI_FLUSH enable bit on Ironlake in my copy of the docs. Bit > > 12 is MBZ on that hardware. > > It's one of those "been there forever" bits. A comment wouldn't hurt, > but we should also put in a doc change request (in fact I think I did > that but it went into a black hole).
Well, by "been there forever", you mean "introduced in: commit a69ffdbfcba8eabf2ca9d384b578e6f28b339c61 Author: Zhenyu Wang <[email protected]> Date: Mon Aug 30 16:12:42 2010 +0800 drm/i915: Enable MI_FLUSH on Sandybridge MI_FLUSH is being deprecated, but still available on Sandybridge. Make sure it's enabled as userspace still uses MI_FLUSH. Signed-off-by: Zhenyu Wang <[email protected]> Cc: [email protected] Signed-off-by: Chris Wilson <[email protected]>" It should be removed on Ironlake, and fixed to be 12 on SNB or just removed.
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