On Mon, 7 Aug 2023 at 08:06, Liu Ying <victor.liu@xxxxxxx> wrote: > > Add the device link when panel bridge is attached and delete the link > when panel bridge is detached. The drm device is the consumer while > the panel device is the supplier. This makes sure that the drm device > suspends eariler and resumes later than the panel device, hence resolves > problems where the order is reversed, like the problematic case mentioned > in the below link. > > Link: https://lore.kernel.org/lkml/CAPDyKFr0XjrU_udKoUKQ_q8RWaUkyqL+8fV-7s1CTMqi7u3-Rg@xxxxxxxxxxxxxx/T/ > Suggested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx> Looks good to me! Just a minor question though, don't we need to manage runtime PM too - or this is solely for system wide suspend/resume? Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Kind regards Uffe > --- > v2->v3: > * Improve commit message s/swapped/reversed/. > > v1->v2: > * Fix bailout for panel_bridge_attach() in case device_link_add() fails. > > drivers/gpu/drm/bridge/panel.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c > index 9316384b4474..a6587d233505 100644 > --- a/drivers/gpu/drm/bridge/panel.c > +++ b/drivers/gpu/drm/bridge/panel.c > @@ -4,6 +4,8 @@ > * Copyright (C) 2017 Broadcom > */ > > +#include <linux/device.h> > + > #include <drm/drm_atomic_helper.h> > #include <drm/drm_bridge.h> > #include <drm/drm_connector.h> > @@ -19,6 +21,7 @@ struct panel_bridge { > struct drm_bridge bridge; > struct drm_connector connector; > struct drm_panel *panel; > + struct device_link *link; > u32 connector_type; > }; > > @@ -60,6 +63,8 @@ static int panel_bridge_attach(struct drm_bridge *bridge, > { > struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge); > struct drm_connector *connector = &panel_bridge->connector; > + struct drm_panel *panel = panel_bridge->panel; > + struct drm_device *drm_dev = bridge->dev; > int ret; > > if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) > @@ -70,6 +75,14 @@ static int panel_bridge_attach(struct drm_bridge *bridge, > return -ENODEV; > } > > + panel_bridge->link = device_link_add(drm_dev->dev, panel->dev, > + DL_FLAG_STATELESS); > + if (!panel_bridge->link) { > + DRM_ERROR("Failed to add device link between %s and %s\n", > + dev_name(drm_dev->dev), dev_name(panel->dev)); > + return -EINVAL; > + } > + > drm_connector_helper_add(connector, > &panel_bridge_connector_helper_funcs); > > @@ -78,6 +91,7 @@ static int panel_bridge_attach(struct drm_bridge *bridge, > panel_bridge->connector_type); > if (ret) { > DRM_ERROR("Failed to initialize connector\n"); > + device_link_del(panel_bridge->link); > return ret; > } > > @@ -100,6 +114,8 @@ static void panel_bridge_detach(struct drm_bridge *bridge) > struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge); > struct drm_connector *connector = &panel_bridge->connector; > > + device_link_del(panel_bridge->link); > + > /* > * Cleanup the connector if we know it was initialized. > * > -- > 2.37.1 >
