Eric Anholt <eric@xxxxxxxxxx> writes:
> When a mipi_dsi_host is registered, the DT is walked to find any child
> nodes with compatible strings. Those get registered as DSI devices,
> and most DSI panel drivers are mipi_dsi_drivers that attach to those nodes.
>
> There is one special case currently, the adv7533 bridge, where the
> bridge probes on I2C, and during the bridge attach step it looks up
> the mipi_dsi_host and registers the mipi_dsi_device (for its own stub
> mipi_dsi_driver).
>
> For the Raspberry Pi panel, though, we also need to attach on I2C (our
> control bus), but don't have a bridge driver. The lack of a bridge's
> attach() step like adv7533 uses means that we aren't able to delay the
> mipi_dsi_device creation until the mipi_dsi_host is present.
>
> To fix this, we extend mipi_dsi_device_register_full() to allow being
> called with a NULL host, which puts the device on a queue waiting for
> a host to appear. When a new host is registered, we fill in the host
> value and finish the device creation process.
>
> v2: Cleanly error out if one attempts to mipi_dsi_attach() without a
> host. Fix handling of DSI with multiple devices, and OF node
> refcounting.
>
> Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_mipi_dsi.c | 63 ++++++++++++++++++++++++++++++++++--------
> include/drm/drm_mipi_dsi.h | 3 ++
> 2 files changed, 54 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 1160a579e0dc..77d439254da6 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -295,6 +308,27 @@ int mipi_dsi_host_register(struct mipi_dsi_host *host)
>
> mutex_lock(&host_lock);
> list_add_tail(&host->list, &host_list);
> +
> + /* If any DSI devices were registered under our OF node, then
> + * connect our host to it and probe them now.
> + */
> + list_for_each_entry_safe(dsi, temp, &unattached_device_list, list) {
> + struct device_node *host_node = of_get_parent(dsi->dev.of_node);
> +
> + if (!of_node_cmp(host_node->name, "ports"))
> + host_node = of_get_next_parent(host_node);
> +
> + if (host_node == host->dev->of_node) {
> + dsi->host = host;
> + dsi->dev.parent = host->dev;
> + device_initialize(&dsi->dev);
> +
> + mipi_dsi_device_add(dsi);
> + list_del_init(&dsi->list);
> + }
> +
> + of_node_put(host_node);
> + }
Kbuild test caught that of_get_next_parent() isn't defined for
!CONFIG_OF, so I've put this loop under IS_ENABLED(CONFIG_OF) for v3.
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