On 09.07.2018 15:48, Heiko Stuebner wrote: > When the panel-driver is build as a module it currently fails hard as the > panel cannot be probed directly: > > dw_mipi_dsi_bind() > __dw_mipi_dsi_probe() > creates dsi bus > creates panel device > triggers panel module load > panel not probed (module not loaded or panel probe slow) > drm_bridge_attach > fails with -EINVAL due to empty panel_bridge > > Additionally the panel probing can run concurrently with dsi bringup > making it possible that the panel can already be found but dsi-attach > hasn't finished running. > > The newly added function provides the ability for glue drivers to > check if a dsi device was actually attached and also protects > the attach part to prevent concurrency issues from panel-assignment > and drm_bridge_create. > > Using that check glue drivers are able to for example defer probe/bind > in the case that the panel is not completely set up yet. > > Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx> > --- > drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 25 +++++++++++++++++++ > include/drm/bridge/dw_mipi_dsi.h | 1 + > 2 files changed, 26 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > index bb4aeca5c0f9..88fed22ff3f6 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > @@ -12,6 +12,7 @@ > #include <linux/component.h> > #include <linux/iopoll.h> > #include <linux/module.h> > +#include <linux/mutex.h> > #include <linux/of_device.h> > #include <linux/pm_runtime.h> > #include <linux/reset.h> > @@ -219,6 +220,7 @@ struct dw_mipi_dsi { > struct drm_bridge bridge; > struct mipi_dsi_host dsi_host; > struct drm_bridge *panel_bridge; > + struct mutex panel_mutex; > struct device *dev; > void __iomem *base; > > @@ -296,10 +298,14 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host, > return PTR_ERR(bridge); > } > > + mutex_lock(&dsi->panel_mutex); > + > dsi->panel_bridge = bridge; > > drm_bridge_add(&dsi->bridge); > > + mutex_unlock(&dsi->panel_mutex); > + > return 0; > } > > @@ -308,13 +314,30 @@ static int dw_mipi_dsi_host_detach(struct mipi_dsi_host *host, > { > struct dw_mipi_dsi *dsi = host_to_dsi(host); > > + mutex_lock(&dsi->panel_mutex); > + > + dsi->panel_bridge = NULL; > drm_of_panel_bridge_remove(host->dev->of_node, 1, 0); > > drm_bridge_remove(&dsi->bridge); > > + mutex_unlock(&dsi->panel_mutex); > + > return 0; > } > > +bool dw_mipi_dsi_device_attached(struct dw_mipi_dsi *dsi) > +{ > + bool output; > + > + mutex_lock(&dsi->panel_mutex); > + output = !!dsi->panel_bridge; > + mutex_unlock(&dsi->panel_mutex); > + > + return output; > +} > +EXPORT_SYMBOL_GPL(dw_mipi_dsi_device_attached); The function does not make sense. After releasing panel_mutex device can be detached/(re-)attached multiple times. Ie it reports useless information. Of course in most cases it will work as expected, but for sure it is not bulletproof. Regards Andrzej > + > static void dw_mipi_message_config(struct dw_mipi_dsi *dsi, > const struct mipi_dsi_msg *msg) > { > @@ -867,6 +890,8 @@ __dw_mipi_dsi_probe(struct platform_device *pdev, > dsi->dev = dev; > dsi->plat_data = plat_data; > > + mutex_init(&dsi->panel_mutex); > + > if (!plat_data->phy_ops->init || !plat_data->phy_ops->get_lane_mbps) { > DRM_ERROR("Phy not properly configured\n"); > return ERR_PTR(-ENODEV); > diff --git a/include/drm/bridge/dw_mipi_dsi.h b/include/drm/bridge/dw_mipi_dsi.h > index 6d7f8eb5d9f2..131ff2569ed4 100644 > --- a/include/drm/bridge/dw_mipi_dsi.h > +++ b/include/drm/bridge/dw_mipi_dsi.h > @@ -31,6 +31,7 @@ struct dw_mipi_dsi_plat_data { > void *priv_data; > }; > > +bool dw_mipi_dsi_device_attached(struct dw_mipi_dsi *dsi); > struct dw_mipi_dsi *dw_mipi_dsi_probe(struct platform_device *pdev, > const struct dw_mipi_dsi_plat_data > *plat_data); _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel