Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760588AbbLCPdx (ORCPT ); Thu, 3 Dec 2015 10:33:53 -0500 Received: from mail9.pr.hu ([87.242.0.9]:58385 "EHLO mail9.pr.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756289AbbLCPdw (ORCPT ); Thu, 3 Dec 2015 10:33:52 -0500 X-Greylist: delayed 2129 seconds by postgrey-1.27 at vger.kernel.org; Thu, 03 Dec 2015 10:33:51 EST Subject: Re: [PATCH] drm/radeon: Retry DDC probing on DVI on failure if we got an HPD interrupt To: cpaul@redhat.com, Alex Deucher , =?UTF-8?Q?Christian_K=c3=b6nig?= , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <1448034740-30193-1-git-send-email-cpaul@redhat.com> Cc: Jerome Glisse , Benjamin Tissoires From: Boszormenyi Zoltan Message-ID: <5660587E.7050801@pr.hu> Date: Thu, 3 Dec 2015 15:58:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1448034740-30193-1-git-send-email-cpaul@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Spam-Score: 0.2 (/) X-Scan-Signature: 4504fbbec4e21e79d85e2024c7bc7f5e X-Spam-Tracer: backend.mail.pr.hu 0.2 20151203145814Z Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5346 Lines: 121 2015-11-20 16:52 keltezéssel, cpaul@redhat.com írta: > From: Stephen Chandler Paul > > HPD signals on DVI ports can be fired off before the pins required for > DDC probing actually make contact, due to the pins for HPD making > contact first. This results in a HPD signal being asserted but DDC > probing failing, resulting in hotplugging occasionally failing. > > This is somewhat rare on most cards (depending on what angle you plug > the DVI connector in), but on some cards it happens constantly. The > Radeon R5 on the machine used for testing this patch for instance, runs > into this issue just about every time I try to hotplug a DVI monitor and > as a result hotplugging almost never works. > > Rescheduling the hotplug work for a second when we run into an HPD > signal with a failing DDC probe usually gives enough time for the rest > of the connector's pins to make contact, and fixes this issue. > > Signed-off-by: Stephen Chandler Paul > --- > So this one has kind of been a tough sell with Jerome, mostly because it's > somewhat of a hack. Unfortunately however I've managed to find machines where > DVI hotplugging literally doesn't work without a patch like this. We've already > tried a couple of ways of handling the situation of retriggering ddc probes: > > * Trying the DDC probe in the radeon_dvi_detect() function multiple times. > * Trying to reschedule the hotplug_work task whenever DDC probing fails on DVI > but we got a hpd signal (this ended up being a much more complicated patch > then anticipated) > * Doing what we do right now, which is just triggering userspace to rescan all > the ports when the hpd signal is asserted by the DVI port but there's no DDC > probe, and repeating until at least a second passes. > > All of these actually work, but I guess it's a question of which one is less of > a hack. If anyone here can think of a cleaner way of handling this feel free to > let me know. > > drivers/gpu/drm/radeon/radeon.h | 3 +++ > drivers/gpu/drm/radeon/radeon_connectors.c | 20 +++++++++++++++++--- > drivers/gpu/drm/radeon/radeon_irq_kms.c | 2 ++ > 3 files changed, 22 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h > index b6cbd81..d63f0fe 100644 > --- a/drivers/gpu/drm/radeon/radeon.h > +++ b/drivers/gpu/drm/radeon/radeon.h > @@ -2460,6 +2460,9 @@ struct radeon_device { > /* amdkfd interface */ > struct kfd_dev *kfd; > > + /* last time we received an hpd signal */ > + unsigned long hpd_time; > + > struct mutex mn_lock; > DECLARE_HASHTABLE(mn_hash, 7); > }; > diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c > index 5a2cafb..4ee9440 100644 > --- a/drivers/gpu/drm/radeon/radeon_connectors.c > +++ b/drivers/gpu/drm/radeon/radeon_connectors.c > @@ -1228,19 +1228,33 @@ radeon_dvi_detect(struct drm_connector *connector, bool force) > const struct drm_encoder_helper_funcs *encoder_funcs; > int i, r; > enum drm_connector_status ret = connector_status_disconnected; > - bool dret = false, broken_edid = false; > + bool dret = false, broken_edid = false, hpd_unchanged; > > r = pm_runtime_get_sync(connector->dev->dev); > if (r < 0) > return connector_status_disconnected; > > - if (!force && radeon_check_hpd_status_unchanged(connector)) { > + hpd_unchanged = radeon_check_hpd_status_unchanged(connector); > + if (!force && hpd_unchanged) { > ret = connector->status; > goto exit; > } > > - if (radeon_connector->ddc_bus) > + if (radeon_connector->ddc_bus) { > dret = radeon_ddc_probe(radeon_connector, false); > + > + /* Sometimes the pins required for the DDC probe on DVI > + * connectors don't make contact at the same time that the ones > + * for HPD do. If the DDC probe fails even though we had an HPD > + * signal, signal userspace to try again */ > + if (!dret && !hpd_unchanged && > + connector->status != connector_status_connected && > + time_before(jiffies, rdev->hpd_time + msecs_to_jiffies(1000))) { > + DRM_DEBUG_KMS("%s: hpd asserted but ddc probe failed, retrying\n", > + connector->name); > + drm_sysfs_hotplug_event(dev); > + } > + } > if (dret) { > radeon_connector->detected_by_load = false; > radeon_connector_free_edid(connector); > diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c > index 171d3e4..579c22c 100644 > --- a/drivers/gpu/drm/radeon/radeon_irq_kms.c > +++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c > @@ -79,6 +79,8 @@ static void radeon_hotplug_work_func(struct work_struct *work) > struct drm_mode_config *mode_config = &dev->mode_config; > struct drm_connector *connector; > > + rdev->hpd_time = jiffies; > + > /* we can race here at startup, some boards seem to trigger > * hotplug irqs when they shouldn't. */ > if (!rdev->mode_info.mode_config_initialized) Does this patch help in case I use a DP-2-DVI-D or HDMI-2-DVI-D converter cable? Thanks in advance, Zoltán Böszörményi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/