From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Gesang Subject: Re: [bisect] regression in suspend with i915 on 82852/855GM Date: Thu, 25 Jun 2015 22:38:21 +0200 Message-ID: <20150625203821.GA14123@acheron> References: <20150623222648.GD12335@acheron> <87wpysz0s0.fsf@intel.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0349739025==" Return-path: Received: from relay.uni-heidelberg.de (relay.uni-heidelberg.de [129.206.100.212]) by gabe.freedesktop.org (Postfix) with ESMTP id 39BD56E280 for ; Thu, 25 Jun 2015 14:19:47 -0700 (PDT) In-Reply-To: <87wpysz0s0.fsf@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Jani Nikula Cc: daniel.vetter@intel.com, intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============0349739025== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="oyUTqETQ0mS9luUI" Content-Disposition: inline --oyUTqETQ0mS9luUI Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable =C2=B7=C2=B7=C2=B7=C2=B7=C2=B7=C2=B7=C2=B7=C2=B7=C2=B7 > On Wed, 24 Jun 2015, Philipp Gesang wrote: > > Hi, > > > > suspend/resume results in the backlight not coming back to life > > on my X40 laptop with an =E2=80=9CDisplay controller: Intel Corporation > > 82852/855GM Integrated Graphics Device=E2=80=9D. > > > > I bisected the issue. Apparently, commit > > b0cd324faed23d10d66ba6ade66579c681feef6f introduced the problem. > > > > Author: Jani Nikula > > Date: Wed Nov 12 16:25:43 2014 +0200 > > > > drm/i915: don't save/restore backlight hist ctl registers > > > > I can confirm that suspend works as expected with a 4.1 kernel if > > the lines to dump/undump the BLC_HIST_CTL register are > > reintroduced; see the attached patch. (According to a web search, > > the same issue seems to have arisen before in 2009, see [1].) > > > > Let me know if you=E2=80=99d like me to run further tests on that > > particular hardware. >=20 > Please run 'intel_reg read 0x61260' after resume both on the patched and > unpatched kernel to see what the hardware wants. The tool is in the > intel-gpu-tools package [1]. Nice tool. With a vanilla kernel I get a value of 0x80000000 before suspend and 0x00000000 after resume. With the patched kernel it=E2=80=99s 0x80000000 before and after. On the vanilla kernel, issuing ``intel_reg write 0x61260 0x80000000``=20 after resume turns the backlight back on. Best, Philipp --oyUTqETQ0mS9luUI Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCgAGBQJVjGa9AAoJELdcG6d+hz92uyYP/A+pfFfBN6EQuKdiP/sGDwJb 1udnYcl0kmw7J7A9ZBO+cuRGpH1jJUABImne1HpEAIAl6ajPy6eCLwpxvxMQBOtx qOGr3sApNlaa+qviKq+dU+z44btjkORAfXx2u2THIuNmc9N6G8wiethAN+Otp/xV A6yTgMwLzBg4LnkCNNAjK1kV320BRXzwEuLEN2iDW7BKik44gQVgrs4vNqpBu1XR iH47yYxEKZFmF9YjEhSlFqHFW4gPM9ypSQOAfPKpI8/lF5OqM1j+JuQ4P/J/7da8 c2yIM9LOhiRMSbjbdH2YMuQx+zsoBEnD+GcfqicQxYvJshtGbyZBcRMKdvtVBaEA klD8XqEHdxKOUIagoGBq0gMqhxECrQhK9WYTOtvlSm5l7amv8ynEgds3oauo8Jnh A+f9V4ZrgrcPAzLgIxhIHXwmTn/38LbfroHo8s0yQ9CT+OlvCw2iEj/LoUhzuAcc XrLxCy4OO6QB1ZDVt80E0bJYcNBOnarvwTTCunzFTRupg8lUrWjEfE2ZmxLAnlGI PnTLhbgoXvsSvUALGY+WfVccKcgtSuVtousWZjJn1nsMUCyRwGpQhayeAgFWuRzO k8cXF0dUzWnCJfRPBBNq9iOgsshCvqNaQhkRWFHGhgTaSHK1grIbiylqwJi3Ld5p fF75oxllk7dvIwGa2mkw =yaRN -----END PGP SIGNATURE----- --oyUTqETQ0mS9luUI-- --===============0349739025== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KSW50ZWwtZ2Z4 IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0 cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9pbnRlbC1nZngK --===============0349739025==--