Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750814AbdGYGxf (ORCPT ); Tue, 25 Jul 2017 02:53:35 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:34687 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750761AbdGYGxe (ORCPT ); Tue, 25 Jul 2017 02:53:34 -0400 Date: Tue, 25 Jul 2017 08:53:28 +0200 From: Daniel Vetter To: Paul Kocialkowski Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, Daniel Vetter Subject: Re: [PATCH 1/2] drm/edid: Add helper to detect whether EDID changed Message-ID: <20170725065328.fhe75lpunqn7vcqv@phenom.ffwll.local> Mail-Followup-To: Paul Kocialkowski , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, Daniel Vetter References: <20170724145447.23449-1-paul.kocialkowski@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170724145447.23449-1-paul.kocialkowski@linux.intel.com> X-Operating-System: Linux phenom 4.11.0-2-amd64 User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3459 Lines: 106 On Mon, Jul 24, 2017 at 05:54:46PM +0300, Paul Kocialkowski wrote: > This adds a common drm helper to detect whether the EDID changed from > the last known cached one. This is useful help detect that a monitor was > changed during a suspend/resume cycle. > > When that happens (a monitor is replaced by another one during suspend), > no hotplug event will be triggered so the change will not be caught at > resume time. Detecting that the EDID changed allows detecting it. > > Signed-off-by: Paul Kocialkowski I can't find the older mails I've typed about this, but the plan we've discussed a while back was: - Add a generational counter to each connector, maybe even expose it to userspace. - Increment that counter every time something changed, e.g. connector->status in the propbe helpers, or when attaching a new edid with the set_edid helper. - Tada, no changes needed to drivers, and easily extensible to other things than edid! Cheers, Daniel > --- > drivers/gpu/drm/drm_edid.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ > include/drm/drm_edid.h | 3 +++ > 2 files changed, 48 insertions(+) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 6bb6337be920..f6ce8bc2907a 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -5036,3 +5036,48 @@ static void drm_get_displayid(struct drm_connector *connector, > } > return; > } > + > +/** > + * drm_check_edid_changed - Check whether the EDID changed since the last update > + * @connector: connector we're probing > + * @adapter: I2C adapter to use for DDC > + * > + * Check whether the EDID changed since the last time it was updated in the > + * drm blob cache. > + * > + * Return: A boolean indicating whether a change happened or not. > + */ > +bool drm_check_edid_changed(struct drm_connector *connector, > + struct i2c_adapter *adapter) > +{ > + struct drm_property_blob *edid_blob; > + struct edid *edid_stored; > + struct edid *edid_read; > + int ret = 0; > + > + if (!connector->edid_blob_ptr) > + return false; > + > + edid_blob = drm_property_blob_get(connector->edid_blob_ptr); > + if (!edid_blob) > + return false; > + > + if (!edid_blob->data || edid_blob->length != sizeof(struct edid)) > + goto out; > + > + edid_stored = (struct edid *) edid_blob->data; > + > + edid_read = drm_get_edid(connector, adapter); > + if (!edid_read) > + goto out; > + > + ret = memcmp(edid_stored, edid_read, sizeof(struct edid)); > + > + kfree(edid_read); > + > +out: > + drm_property_blob_put(edid_blob); > + > + return ret != 0; > +} > +EXPORT_SYMBOL_GPL(drm_check_edid_changed); > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h > index 1e1908a6b1d6..593a97b269c3 100644 > --- a/include/drm/drm_edid.h > +++ b/include/drm/drm_edid.h > @@ -485,4 +485,7 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name, > struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev, > int hsize, int vsize, int fresh, > bool rb); > +bool drm_check_edid_changed(struct drm_connector *connector, > + struct i2c_adapter *adapter); > + > #endif /* __DRM_EDID_H__ */ > -- > 2.13.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch