From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com ([192.55.52.115]:9348 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751611AbcDRIo4 (ORCPT ); Mon, 18 Apr 2016 04:44:56 -0400 Date: Mon, 18 Apr 2016 11:44:51 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Imre Deak Cc: intel-gfx@lists.freedesktop.org, stable@vger.kernel.org Subject: Re: [PATCH 2/4] drm/i915: Fix system resume if PCI device remained enabled Message-ID: <20160418084451.GB4329@intel.com> References: <1460963062-13211-1-git-send-email-imre.deak@intel.com> <1460963062-13211-3-git-send-email-imre.deak@intel.com> <20160418082822.GY4329@intel.com> <1460968358.3172.17.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1460968358.3172.17.camel@intel.com> Sender: stable-owner@vger.kernel.org List-ID: On Mon, Apr 18, 2016 at 11:32:38AM +0300, Imre Deak wrote: > On ma, 2016-04-18 at 11:28 +0300, Ville Syrj�l� wrote: > > On Mon, Apr 18, 2016 at 10:04:20AM +0300, Imre Deak wrote: > > > During system resume we depended on pci_enable_device() also > > > putting the > > > device into PCI D0 state. This won't work if the PCI device was > > > already > > > enabled but still in D3 state. This is because pci_enable_device() > > > is > > > refcounted and will not change the HW state if called with a non- > > > zero > > > refcount. Leaving the device in D3 will make all subsequent device > > > accesses fail. > > > > > > This didn't cause a problem most of the time, since we resumed with > > > an > > > enable refcount of 0. But it fails at least after module reload > > > because > > > after that we also happen to leak a PCI device enable reference: > > > During > > > probing we call drm_get_pci_dev() which will enable the PCI device, > > > but > > > during device removal drm_put_dev() won't disable it. This is a bug > > > of > > > its own in DRM core, but without much harm as it only leaves the > > > PCI > > > device enabled. Fixing it is also a bit more involved, due to DRM > > > mid-layering and because it affects non-i915 drivers too. The fix > > > in > > > this patch is valid regardless of the problem in DRM core. > > > > > > CC: Ville Syrj�l� > > > CC: stable@vger.kernel.org > > > Signed-off-by: Imre Deak > > > --- > > > �drivers/gpu/drm/i915/i915_drv.c | 9 ++++++++- > > > �1 file changed, 8 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.c > > > b/drivers/gpu/drm/i915/i915_drv.c > > > index d550ae2..7eaa93e 100644 > > > --- a/drivers/gpu/drm/i915/i915_drv.c > > > +++ b/drivers/gpu/drm/i915/i915_drv.c > > > @@ -803,7 +803,7 @@ static int i915_drm_resume(struct drm_device > > > *dev) > > > �static int i915_drm_resume_early(struct drm_device *dev) > > > �{ > > > � struct drm_i915_private *dev_priv = dev->dev_private; > > > - int ret = 0; > > > + int ret; > > > � > > > � /* > > > � �* We have a resume ordering issue with the snd-hda driver > > > also > > > @@ -814,6 +814,13 @@ static int i915_drm_resume_early(struct > > > drm_device *dev) > > > � �* FIXME: This should be solved with a special hdmi sink > > > device or > > > � �* similar so that power domains can be employed. > > > � �*/ > > > + > > > + ret = pci_set_power_state(dev->pdev, PCI_D0); > > > + if (ret) { > > > + DRM_ERROR("failed to set PCI D0 power state > > > (%d)\n", ret); > > > + goto out; > > > + } > > > > Hmm. Doesn't this already happen from pci bus resume_noirq hook? > > It does, but not during thaw_noirq. Maybe put that into a comment? If we ever get to dropping the device state frobbery from freeze/thaw, then we should also be able to throw out the pci_set_power_state() call as well. Perhaps we should have some asserts about the state of the PCI device? > > > > > > + > > > � if (pci_enable_device(dev->pdev)) { > > > � ret = -EIO; > > > � goto out; > > > -- > > > 2.5.0 > > -- Ville Syrj�l� Intel OTC