On Thu, 2019-04-11 at 17:00 +0100, Lisovskiy, Stanislav wrote:
> On Thu, 2019-04-11 at 17:36 +0300, Gwan-gyeong Mun wrote:
> > The hotplug detection routine of drm_helper_hpd_irq_event() can
> > detect
> > changing of status of connector, but it can not detect changing of
> > edid.
> >
> > Following scenario requires detection of changing of edid.
> >
> > 1) plug display device to a connector
> > 2) system suspend
> > 3) unplug 1)'s display device and plug the other display device to
> > a
> > connector
> > 4) system resume
> >
> > It adds edid check routine when a connector status still remains as
> > "connector_status_connected".
> >
> > v2: Add NULL check before comparing of EDIDs.
> > v3: Make it as part of existing drm_helper_hpd_irq_event() (Stan,
> > Mika)
> > v4: Rebased
> > v5: Use a cached edid property blob data of connector instead of
> > adding
> > a new detected_edid variable. (Maarten)
> > Add an using of reference count for getting a cached edid
> > property
> > blob data. (Maarten)
> >
> > Testcase: igt/kms_chamelium/hdmi-edid-change-during-hibernate
> > Testcase: igt/kms_chamelium/hdmi-edid-change-during-suspend
> > Testcase: igt/kms_chamelium/dp-edid-change-during-hibernate
> > Testcase: igt/kms_chamelium/dp-edid-change-during-suspend
> >
> > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_probe_helper.c | 34
> > +++++++++++++++++++++++++++++-
> > 1 file changed, 33 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c
> > b/drivers/gpu/drm/drm_probe_helper.c
> > index 6fd08e04b323..27ad7f3dabb7 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -742,7 +742,16 @@ EXPORT_SYMBOL(drm_kms_helper_poll_fini);
> > * panels.
> > *
> > * This helper function is useful for drivers which can't or don't
> > track hotplug
> > - * interrupts for each connector.
> > + * interrupts for each connector. And it also supports a detection
> > of changing
> > + * of edid on between suspend and resume when a connector status
> > still remains
> > + * as "connector_status_connected".
> > + *
> > + * Following scenario requires detection of changing of edid.
> > + * 1) plug display device to a connector
> > + * 2) system suspend
> > + * 3) unplug 1)'s display device and plug the other display
> > device
> > to a
> > + * connector
> > + * 4) system resume
> > *
> > * Drivers which support hotplug interrupts for each connector
> > individually and
> > * which have a more fine-grained detect logic should bypass this
> > code and
> > @@ -760,6 +769,7 @@ bool drm_helper_hpd_irq_event(struct drm_device
> > *dev)
> > struct drm_connector *connector;
> > struct drm_connector_list_iter conn_iter;
> > enum drm_connector_status old_status;
> > + struct drm_property_blob *old_edid_blob_ptr;
> > bool changed = false;
> >
> > if (!dev->mode_config.poll_enabled)
> > @@ -774,6 +784,11 @@ bool drm_helper_hpd_irq_event(struct
> > drm_device
> > *dev)
> >
> > old_status = connector->status;
> >
> > + if (connector->edid_blob_ptr)
> > + old_edid_blob_ptr =
> > drm_property_blob_get(connector->edid_blob_ptr);
> > + else
> > + old_edid_blob_ptr = NULL;
> > +
> > connector->status = drm_helper_probe_detect(connector,
> > NULL, false);
> > DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s
> > to %s\n",
> > connector->base.id,
> > @@ -782,6 +797,23 @@ bool drm_helper_hpd_irq_event(struct
> > drm_device
> > *dev)
> > drm_get_connector_status_name(connector-
> > > status));
> > if (old_status != connector->status)
> > changed = true;
> > +
> > + /* Check changing of edid when a connector status still
> > remains
> > + * as "connector_status_connected".
> > + */
> > + if (old_edid_blob_ptr && connector->edid_blob_ptr &&
>
> I guess you don't need to check both old_edid_blob_ptr && connector-
> > edid_blob_ptr here. Because if old_edid_blob_ptr is not NULL - it
> means that connector->edid_blob_ptr was not NULL for sure. See the
> condition you have added above.
> I mean this one:
>
> > + if (connector->edid_blob_ptr)
> > + old_edid_blob_ptr =
> > drm_property_blob_get(connector->edid_blob_ptr);
> > + else
> > + old_edid_blob_ptr = NULL;
>
> So I would check only old_edid_blob_ptr for not being NULL here.
>
>
Hi Stan,
Thank you for checking it.
First, drivers could set edid_blob_ptr to NULL with
drm_connector_update_edid_property().
And drm_helper_probe_detect() could lead updating of an internal edid
of driver and if driver can not get EDID from I2C, it could call
drm_connector_update_edid_property() with NULL.
therefore I think that we should check old and new edid_blob_ptr are
NULL or not.
>
> > + old_status == connector->status &&
> > + old_status == connector_status_connected) {
> > + if (memcmp(old_edid_blob_ptr->data,
> > + connector->edid_blob_ptr->data,
> > + old_edid_blob_ptr->length)) {
> > + changed = true;
> > + DRM_DEBUG_KMS("[CONNECTOR:%d:%s] edid
> > updated\n",
> > + connector->base.id,
> > + connector->name);
> > + }
> > + }
> > + drm_property_blob_put(old_edid_blob_ptr);
> > }
> > drm_connector_list_iter_end(&conn_iter);
> > mutex_unlock(&dev->mode_config.mutex);
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