Re: [PATCH 3/3] drm/msm/dsi: make sure we have panel or bridge earlier

Andrzej Hajda
2019-07-04T06:40:00Z

On 30.06.2019 15:14, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> If we are going to -EPROBE_DEFER due to panel/bridge not probed yet, we
> want to do it before we start touching hardware.

As the evidence shows, if the driver create bus (mipi-dsi), then it
should not defer probing due to lack of sink (panel/bridge), because the
sink will not appear without the bus.

Instead of defer probing you can defer component binding, or if you like
challenges you can implement dynamic sink binding :)

Regards

Andrzej

>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> drivers/gpu/drm/msm/dsi/dsi.h | 2 +-
> drivers/gpu/drm/msm/dsi/dsi_host.c | 30 +++++++++++++--------------
> drivers/gpu/drm/msm/dsi/dsi_manager.c | 9 +++-----
> 3 files changed, 19 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.h b/drivers/gpu/drm/msm/dsi/dsi.h
> index 53bb124e8259..e15e7534ccd9 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.h
> +++ b/drivers/gpu/drm/msm/dsi/dsi.h
> @@ -171,7 +171,7 @@ int msm_dsi_host_set_display_mode(struct mipi_dsi_host *host,
> struct drm_panel *msm_dsi_host_get_panel(struct mipi_dsi_host *host);
> unsigned long msm_dsi_host_get_mode_flags(struct mipi_dsi_host *host);
> struct drm_bridge *msm_dsi_host_get_bridge(struct mipi_dsi_host *host);
> -int msm_dsi_host_register(struct mipi_dsi_host *host, bool check_defer);
> +int msm_dsi_host_register(struct mipi_dsi_host *host);
> void msm_dsi_host_unregister(struct mipi_dsi_host *host);
> int msm_dsi_host_set_src_pll(struct mipi_dsi_host *host,
> struct msm_dsi_pll *src_pll);
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 1ae2f5522979..8e5b0ba9431e 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -1824,6 +1824,20 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi)
> goto fail;
> }
>
> + /*
> + * Make sure we have panel or bridge early, before we start
> + * touching the hw. If bootloader enabled the display, we
> + * want to be sure to keep it running until the bridge/panel
> + * is probed and we are all ready to go. Otherwise we'll
> + * kill the display and then -EPROBE_DEFER
> + */
> + if (IS_ERR(of_drm_find_panel(msm_host->device_node)) &&
> + !of_drm_find_bridge(msm_host->device_node)) {
> + pr_err("%s: no panel or bridge yet\n", __func__);
> + return -EPROBE_DEFER;
> + }
> +
> +
> msm_host->ctrl_base = msm_ioremap(pdev, "dsi_ctrl", "DSI CTRL");
> if (IS_ERR(msm_host->ctrl_base)) {
> pr_err("%s: unable to map Dsi ctrl base\n", __func__);
> @@ -1941,7 +1955,7 @@ int msm_dsi_host_modeset_init(struct mipi_dsi_host *host,
> return 0;
> }
>
> -int msm_dsi_host_register(struct mipi_dsi_host *host, bool check_defer)
> +int msm_dsi_host_register(struct mipi_dsi_host *host)
> {
> struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
> int ret;
> @@ -1955,20 +1969,6 @@ int msm_dsi_host_register(struct mipi_dsi_host *host, bool check_defer)
> return ret;
>
> msm_host->registered = true;
> -
> - /* If the panel driver has not been probed after host register,
> - * we should defer the host's probe.
> - * It makes sure panel is connected when fbcon detects
> - * connector status and gets the proper display mode to
> - * create framebuffer.
> - * Don't try to defer if there is nothing connected to the dsi
> - * output
> - */
> - if (check_defer && msm_host->device_node) {
> - if (IS_ERR(of_drm_find_panel(msm_host->device_node)))
> - if (!of_drm_find_bridge(msm_host->device_node))
> - return -EPROBE_DEFER;
> - }
> }
>
> return 0;
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> index ff39ce6150ad..cd3450dc3481 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> @@ -82,7 +82,7 @@ static int dsi_mgr_setup_components(int id)
> int ret;
>
> if (!IS_DUAL_DSI()) {
> - ret = msm_dsi_host_register(msm_dsi->host, true);
> + ret = msm_dsi_host_register(msm_dsi->host);
> if (ret)
> return ret;
>
> @@ -101,14 +101,11 @@ static int dsi_mgr_setup_components(int id)
> /* Register slave host first, so that slave DSI device
> * has a chance to probe, and do not block the master
> * DSI device's probe.
> - * Also, do not check defer for the slave host,
> - * because only master DSI device adds the panel to global
> - * panel list. The panel's device is the master DSI device.
> */
> - ret = msm_dsi_host_register(slave_link_dsi->host, false);
> + ret = msm_dsi_host_register(slave_link_dsi->host);
> if (ret)
> return ret;
> - ret = msm_dsi_host_register(master_link_dsi->host, true);
> + ret = msm_dsi_host_register(master_link_dsi->host);
> if (ret)
> return ret;
>