From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH v2] drm/i915: Send a hotplug event on resume instead of an IRQ event Date: Wed, 16 Dec 2015 09:33:50 +0100 Message-ID: <20151216083350.GD30437@phenom.ffwll.local> References: <1450211658.8084.11.camel@redhat.com> <1450218356-24028-1-git-send-email-cpaul@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail-wm0-f45.google.com (mail-wm0-f45.google.com [74.125.82.45]) by gabe.freedesktop.org (Postfix) with ESMTPS id 154796E32C for ; Wed, 16 Dec 2015 00:33:54 -0800 (PST) Received: by mail-wm0-f45.google.com with SMTP id l126so27522865wml.1 for ; Wed, 16 Dec 2015 00:33:54 -0800 (PST) Content-Disposition: inline In-Reply-To: <1450218356-24028-1-git-send-email-cpaul@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Lyude Cc: kuddel.mail@gmx.de, Daniel Vetter , open list , "open list:DRM DRIVERS" , Julien Wajsberg , Benjamin Tissoires , Lennart Poettering List-Id: dri-devel@lists.freedesktop.org T24gVHVlLCBEZWMgMTUsIDIwMTUgYXQgMDU6MjU6NTZQTSAtMDUwMCwgTHl1ZGUgd3JvdGU6Cj4g V2UgY3VycmVudGx5IGNhbGwgZHJtX2hlbHBlcl9ocGRfaXJxX2V2ZW50KCkgdG8gaGFuZGxlIHJl cHJvYmluZwo+IGRpc3BsYXlzIG9uIHJlc3VtZSwgaG93ZXZlciBkcm1faGVscGVyX2hwZF9pcnFf ZXZlbnQoKSBvbmx5IGNoZWNrcyB0aGUKPiBzdGF0dXMgb2YgaHBkLiBIUEQgZG9lc24ndCB1cGRh dGUgaWYgdGhlIGRpc3BsYXlzIGNvbm5lY3RlZCBjaGFuZ2VkCj4gYmVmb3JlIHJlc3VtaW5nIHRo ZSBzeXN0ZW0sIGFuZCBhcyBzdWNoIGNhdXNlcyB1cyBub3QgdG8gZGV0ZWN0IGFueQo+IGNvbm5l Y3Rpb24gY2hhbmdlcyBhZnRlciByZXN1bWUuCj4gCj4gVGhpcyBvcmlnaW5hbGx5IHdhc24ndCB0 aGUgY2FzZSBzaW5jZSBkcm0gd291bGQgcmVzZXQgYWxsIG9mIHRoZQo+IGNvbm5lY3RvcnMgdG8g dW5rbm93biBkdXJpbmcgcmVzdW1lIGFuZCBjYXVzZSBhIHJlcHJvYmUgKHNpbmNlIHRoZQo+IGNv bm5lY3RvciBzdGF0dXNlcyB3b3VsZCBjaGFuZ2UpLCBob3dldmVyIHRoaXMgYmVoYXZpb3IgY2hh 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bWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754636AbbLPId4 (ORCPT ); Wed, 16 Dec 2015 03:33:56 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:38683 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753632AbbLPIdx (ORCPT ); Wed, 16 Dec 2015 03:33:53 -0500 Date: Wed, 16 Dec 2015 09:33:50 +0100 From: Daniel Vetter To: Lyude Cc: David Airlie , "open list:DRM DRIVERS" , open list , Daniel Vetter , Rui Matos , Julien Wajsberg , kuddel.mail@gmx.de, Lennart Poettering , Rob Clark , Benjamin Tissoires Subject: Re: [PATCH v2] drm/i915: Send a hotplug event on resume instead of an IRQ event Message-ID: <20151216083350.GD30437@phenom.ffwll.local> Mail-Followup-To: Lyude , David Airlie , "open list:DRM DRIVERS" , open list , Rui Matos , Julien Wajsberg , kuddel.mail@gmx.de, Lennart Poettering , Rob Clark , Benjamin Tissoires References: <1450211658.8084.11.camel@redhat.com> <1450218356-24028-1-git-send-email-cpaul@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1450218356-24028-1-git-send-email-cpaul@redhat.com> X-Operating-System: Linux phenom 4.2.0-1-amd64 User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 15, 2015 at 05:25:56PM -0500, Lyude wrote: > We currently call drm_helper_hpd_irq_event() to handle reprobing > displays on resume, however drm_helper_hpd_irq_event() only checks the > status of hpd. HPD doesn't update if the displays connected changed > before resuming the system, and as such causes us not to detect any > connection changes after resume. > > This originally wasn't the case since drm would reset all of the > connectors to unknown during resume and cause a reprobe (since the > connector statuses would change), however this behavior changed in > 5677d67ae394 ('drm: Stop resetting connector state to unknown'). > > Signed-off-by: Lyude > --- > I did some research into why setting the connector state to unknown was > causing a reprobe and discovered that the fact that this reprobing ever > worked at all was just a coincidence (i915's IRQ handler gets called by the > irq event, notices the state of all the connectors changed since they were > set to unknown, causes a reprobe). This seems to fix everything (including > monitor detection in normal VTs), and I can't figure out any real use now > for us to set everything to unknown so I'm going to go the route of just > sending the hotplug event instead. > > drivers/gpu/drm/i915/i915_drv.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > index 760e0ce..27a6c1b 100644 > --- a/drivers/gpu/drm/i915/i915_drv.c > +++ b/drivers/gpu/drm/i915/i915_drv.c > @@ -792,7 +792,7 @@ static int i915_drm_resume(struct drm_device *dev) > * */ > intel_hpd_init(dev_priv); > /* Config may have changed between suspend and resume */ > - drm_helper_hpd_irq_event(dev); > + drm_kms_helper_hotplug_event(dev); So there's a bunch of things broken in this area, but just from your description it's unclear what exactly. Problems I'm aware of: - hpd_irq_event() only reprobes connectors for which hpd is enabled, which are not all of them. We broke this in commit 816da85a0990c2b52cfffa77637d1c770d6790e9 Author: Daniel Vetter Date: Tue Oct 23 18:23:33 2012 +0000 drm: handle HPD and polled connectors separately which is positively ages ago. Also note that any other driver not using vt switching also suffers from this (atm radeon, nouveau, rockchip, amdgpu). otoh at least from a quick those drivers also don't really bother with reprobing on resume really. - DP MST reprobing is busted in i915 since commit e7d6f7d708290da1b7c92f533444b042c79412e0 Author: Dave Airlie Date: Mon Dec 8 13:23:37 2014 +1000 drm/i915: resume MST after reading back hw state There's some bug reports iirc from Takashi and Ted Tso about this. Your patch won't help for DP MST since we never reprobe MST state from userspace, it only ever happens through interrupt handling. Well mostly, if you completely unplug something then we detect that and throw all the MST stuff over board, but if you e.g. just change a connection in your dock or go from one dock to another we won't detect this. Which one of the above is it? And to what extend do you care about this working everywhere? Sorry that I'm opening a can of worms here. Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch