From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Packard Subject: Re: [PATCH] drm/i915: rip out the HWSTAM missed irq workaround Date: Mon, 09 Jan 2012 18:09:13 -0800 Message-ID: <8662gkb96e.fsf@sumi.keithp.com> References: <1325702445-2231-1-git-send-email-daniel.vetter@ffwll.ch> <1325801514-2129-1-git-send-email-daniel.vetter@ffwll.ch> <86hb04bkog.fsf@sumi.keithp.com> <20120109233952.GJ3723@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1463652774==" Return-path: Received: from keithp.com (home.keithp.com [63.227.221.253]) by gabe.freedesktop.org (Postfix) with ESMTP id 761F39E78C for ; Mon, 9 Jan 2012 18:09:17 -0800 (PST) In-Reply-To: <20120109233952.GJ3723@phenom.ffwll.local> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Daniel Vetter Cc: David Airlie , Daniel Vetter , intel-gfx List-Id: intel-gfx@lists.freedesktop.org --===============1463652774== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" --=-=-= Content-Transfer-Encoding: quoted-printable On Tue, 10 Jan 2012 00:39:52 +0100, Daniel Vetter wrote: > I honestly don't trust my patch, so I'd like to give it as much validation > as possible. Which means: > - Shove it into -next and beat on it there. We can ship current 3.3 with > Eric's workaround - it's not great but at least this works. Actually, sticking your patch in as a fix for 3.3 before RC1 means we'll get loads more testing as more people test the RCs than will ever touch drm-intel-next. Dave Airlie might have an opinion on whether that's reasonable at this stage or not. > - Enable the voodoo and revert the HWSTAM w/a also on snb - there are > orders more snb machines in the wild than pre-production ivbs. I.e. this > hopefully greatly increases our changes to find out whether the voodoo > really works or if it is only pretty decent, but not perfect ducttape. I suspect that the hardware is different enough between IVB and SNB that SNB testing won't tell us all that much though. And, we have a working SNB driver right now, with the HWSTAM work-around in place. I'd be perfectly happy to use HWSTAM on SNB forever and use the forcewake voodoo only on IVB. Yeah, having the voodoo run on SNB would get a lot more testing, but it's not going to increase our confidence on how well it works on IVB, which is the only place it is actually needed. > - See what happens and act accordingly (maybe reinstate the HWSTAM w/a if > it's required). If things really work out when this hits mainline, > backport the voodoo patch, leaving the HWSTAM in place for older > kernels. So, the "nice" thing about the two IVB work-arounds is that they can co-exist in the kernel perfectly happily. We know that your voodoo serves to keep the chip awake for a tiny interval after it has finished drawing (essentially the time from the end of work to the interrupt ack and forcewake disable), so it's not a significant additional power drain. We could leave the code for spinning in place and simply control that with a module parameter. That would allow us to disable it now, and if we find problems (or are particularly paranoid) we could disable it before 3.3 ships with a 1-line patch. > Yep, I'm officially paranoid about this ;-) rc6, forcewake and friends > have simply blown up too often in unpredictable ways ... We love our fancy hardware. The power savings brought about by rc6 are impressive though; I only wish it didn't take so much software support... =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIVAwUBTwudyTYtFsjWk68qAQh99A//S2IpVth60PPh9XtLXbGeTW7Q1zygFCvF 2Q8pWxYKwNg26LY6RBv1qNUJ7TKIB21QZzJ8ufmvNjWUIstKbf/hfOfdno87SRUd bm9NPysfXZmqpFpuv5d0J8zMzXKMNMnEM+fk2hfNjidzq2FEIxP0RmDK5Y/DI/Yo jW1oj9qCwm3pfEkV+XE+q/DGjqbVuVdoiDhknjh6KKXj8N0lnW1R/VrOqLbfl2mH jw1f3xlVldMpdHD10NUtLnsqYToXq5lJj+9rfa9qCMttTz7gJEWYd+i0jvsDy7PB R4cv0ocMH4I1UcCHdxnSKJMWBTFrzAA3JIU5ocrNizWZnoEPoLkQZirYn55HulN3 TuXPTm6PABRSI03q2nlXmiLF+kTVEU/uPEmipWRZtt9TS2lWjo0/LXyrfhn7aos8 WQ76cf61PcY7egnF3orspEQEnJ/Z08J+bRxKBHWycWNjdX4H7cCxJ+82t5TwTcRq 86LehFyP6RfG5JOGi+INa2Y/Xx5CdCmakaKwaZlAlHy0BsZ9fMEvCZuDLVM8gpT/ Q3dR9F6YQe8qEQCJQm1a8dLEVHi+eQvF8aWMNGDjDsusl+adh25m2Hi4ocqLvgAu M5xhNuQxYqySaI7GN0HEM3QYxG5NQNadncpt0miqXl3BtCRQ4XYqaovkpqgEQ7Lw J1AOWrpMkZU= =BRvd -----END PGP SIGNATURE----- --=-=-=-- --===============1463652774== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx --===============1463652774==--