On 14.08.2018 12:26, Heiko Stuebner wrote:
> With the regular means of adding the dsi-component in probe it creates
> a race condition with the panel probing, as the panel device only gets
> created after the dsi-bus got created.
>
> 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.
>
> To solve that cleanly we may want to only create the component after
> the panel has finished probing, by calling component_add from the
> host-attach dsi callback.
>
> As that is specific to glue drivers, add a new struct for host_ops
> so that glue drivers can tell the bridge to call specific functions
> after the common host-attach and before the common host-detach run.
Sometimes I have an impression that core/glue driver architecture with
callbacks to glue drivers is quite complicated, and smells mid-layer
mistake :), I wonder if simple bunch of helpers with some base object
wouldn't be better, but this is subject for other discussion.
>
> Suggested-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> ---
> drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 15 +++++++++++++++
> include/drm/bridge/dw_mipi_dsi.h | 8 ++++++++
> 2 files changed, 23 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..3962e5d84e1e 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -270,6 +270,7 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host,
> struct mipi_dsi_device *device)
> {
> struct dw_mipi_dsi *dsi = host_to_dsi(host);
> + const struct dw_mipi_dsi_plat_data *pdata = dsi->plat_data;
> struct drm_bridge *bridge;
> struct drm_panel *panel;
> int ret;
> @@ -300,6 +301,12 @@ static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host,
>
> drm_bridge_add(&dsi->bridge);
>
> + if (pdata->host_ops && pdata->host_ops->attach) {
> + ret = pdata->host_ops->attach(pdata->priv_data, device);
> + if (ret < 0)
> + return ret;
It could be replaced by:
return pdata->host_ops->attach(pdata->priv_data, device);
But no strong feelings. With or without the change:
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
--
Regards
Andrzej
> + }
> +
> return 0;
> }
>
> @@ -307,6 +314,14 @@ static int dw_mipi_dsi_host_detach(struct mipi_dsi_host *host,
> struct mipi_dsi_device *device)
> {
> struct dw_mipi_dsi *dsi = host_to_dsi(host);
> + const struct dw_mipi_dsi_plat_data *pdata = dsi->plat_data;
> + int ret;
> +
> + if (pdata->host_ops && pdata->host_ops->detach) {
> + ret = pdata->host_ops->detach(pdata->priv_data, device);
> + if (ret < 0)
> + return ret;
> + }
>
> drm_of_panel_bridge_remove(host->dev->of_node, 1, 0);
>
> diff --git a/include/drm/bridge/dw_mipi_dsi.h b/include/drm/bridge/dw_mipi_dsi.h
> index 6d7f8eb5d9f2..a9c03099cf3e 100644
> --- a/include/drm/bridge/dw_mipi_dsi.h
> +++ b/include/drm/bridge/dw_mipi_dsi.h
> @@ -19,6 +19,13 @@ struct dw_mipi_dsi_phy_ops {
> unsigned int *lane_mbps);
> };
>
> +struct dw_mipi_dsi_host_ops {
> + int (*attach)(void *priv_data,
> + struct mipi_dsi_device *dsi);
> + int (*detach)(void *priv_data,
> + struct mipi_dsi_device *dsi);
> +};
> +
> struct dw_mipi_dsi_plat_data {
> void __iomem *base;
> unsigned int max_data_lanes;
> @@ -27,6 +34,7 @@ struct dw_mipi_dsi_plat_data {
> const struct drm_display_mode *mode);
>
> const struct dw_mipi_dsi_phy_ops *phy_ops;
> + const struct dw_mipi_dsi_host_ops *host_ops;
>
> void *priv_data;
> };
